Troubleshooting and Maintaining Your RV’s Air Conditioner

Updated on January 24, 2019
Randy Godwin profile image

Randy is a lifelong lover of the outdoors and especially camping. His articles are intended to help the RVer save money and time on repairs.

A new Coleman 13,500 BTU A/C unit ready to install.
A new Coleman 13,500 BTU A/C unit ready to install. | Source

The rooftop air conditioners used on motorhomes are made to give many years of dependable cooling efficiency, especially if you maintain them.

This article has two parts: first, how to troubleshoot your AC and decide which parts to replace or service; and second, how to maintain your AC.

These repair and maintenance tips are very simple to follow, even for those without much hands-on experience.

Part 1: Troubleshooting

Some Background: How Your AC Works

If you are unfamiliar with how a motorhome air conditioning system works, this companion article will help you understand which parts of the motorhome rooftop air conditioner unit to check, service, and repair.

Briefly, your air conditioner, which may be combined with a heating system, includes a compressor—to circulate a cooling fluid like Freon through the coils and fins of the condenser—and a fan, to blow cooled air through the RV. The fan and compressor are turned on and off by a thermostat—a switch attached to a thermometer—and kick-started by one or more capacitors. The thermostat and other controls are run by the vehicle's 12-volt electrical system.

Where to Start Investigating

Many problems your air conditioner might have—sluggish behavior, turning off prematurely--can be resolved by checking out the electrical system in order, going first through the possibilities that are easiest to resolve. These easier choices often solve the problem. If they don't, you can investigate further so you can decide if you need to replace the big items like the fan and the compressor or get a whole new AC unit.

First, we'll address the common electrical issues.

A Precaution

Before attempting any maintenance or repairs on the rooftop AC unit, be sure to switch off the electrical supply to the unit, either by tripping the breaker or by unplugging the motorhome from the electrical receptacle.

RV AC Issues You Can Troubleshoot Yourself

  • If your AC does nothing and makes no noise, make sure your unit and its controls are getting power.
  • If your AC fan or compressor is slow to start, doesn't blow any air, blows weakly, blows only warm air, stops after a while, dims your lights, or trips your breaker, you should first check your capacitors and replace them if needed. 

  • If there's no air blowing, check the fan capacitor; if there's no cooling, check the compressor capacitor.
  • If the capacitor is okay, you should look at whether the thermostat is getting power by checking whether the 12-volt appliaces work.
  • You can check the function of the thermostat if it's wall-mounted. If the unit only works when thermostat wires are touching, the thermostat is bad. The thermostat is easy to replace.

  • If the capacitor and thermostat are okay, the control board may be bad.
  • If the control board is okay, you may have to replace the fan motor or the compressor.

  • If the fan only works at certain speeds, the fan motor may be bad.
  • You can have the fan motor rebuilt (if it's not the sleeved-bearing type). Or you can replace the fan motor yourself if the unit is in good shape otherwise.
  • If the compressor is bad, it should probably be replaced, not fixed.
  • If your system drips or overheats, the coils may need cleaning.
  • If the roof AC leaks, the bolts may be loose or the gasket may be leaking.
  • If the system is very cold or ice builds up, it may be low on Freon.
  • If the unit is noisy, something out of place may be interfering with its motors; you can check by removing the shroud.

The First Step: Is There Power?

If your unit does not react at all—does not go on and does not make noise—you will want to make sure it is getting power. Look in the 12-volt panel and check that the fuse has not blown or the breaker has not tripped. The 12-volt power system runs the controls to the AC including the thermostat.

Running the AC unit itself draws a lot of higher-voltage power, maybe too much for a 15-amp power pole, and if there are two modern rooftop units they may draw too much for the 30-amp power supply provided at many campgrounds. If the unit draws more than the system can provide, the breaker or fuse will shut off. Fortunately, many campgrounds and RV parks now provide 50-amp service for modern multi-unit AC systems.

The thermostat is run by 12-volt power, like your motor home's lights and vent fans. If these accessories aren't working either, there is something wrong with the 12-volt power. A breaker may be bad or there may be a loose connection in the breaker box. Occasionally the power converter that converts your higher-voltage power to 12-volt power is bad.

Next: Consider the Capacitors

If the fan or the compressor fail to start, it is possible the starting capacitor is malfunctioning. A bad capacitor can cause a variety of symptoms: the AC unit merely hums and "tries" to start, it runs a few minutes then trips a breaker, the fan won't start without a push, or it blows only hot air because the compressor can't start.

The capacitor stores electricity to give both the fan motor and the compressor an extra boost whenever the RV AC unit starts. It is not unusual for the capacitor to go bad, especially if the RV sits unused for a while, and not be able to provide that little push that gets the motors going. On occasion a bad capacitor will explode with a puff of smoke without damaging the rest of the unit.

There may be one capacitor for both compressor and fan, two capacitors (one for each part), or even three or more all together. A capacitor is often shaped like a small battery, flask, or button.

If you have a multimeter in your tool kit, you can use it to test the capacitor. A good capacitor should show a random value on the multimeter that slowly decreases the longer you keep the probes in place.

A bad capacitor is easy to replace. Check the required voltage and model numbers on the old capacitor when ordering a new one.

When replacing it, make sure the power is off. Observe which wires go into it where, and make a note so you can install the new one exactly the same way. Don't touch its terminals with your bare hands. Before you throw the old capacitor away, drain out its electrical charge by connecting its terminals with a screwdriver (make sure the screwdriver handle you are holding is insulated).

Very often, your AC unit will start and run fine after you replace a capacitor.

A capacitor.  Often a cylindrical container, but yours may differ.
A capacitor. Often a cylindrical container, but yours may differ. | Source

Next: Check the Thermostat and Switches

A bad thermostat is another possibility. If you have a wall-mounted thermostat, you can check it by checking its voltage with your multimeter. If the unit only goes on when you touch the thermostat wires to each other, the thermostat is definitely bad.

If the thermostat and capacitors are all okay but the AC still doesn't work, you may have a bad control board.

Thermostats and switches may be purchased online by finding the correct model and serial numbers before ordering the new parts. These items are easy to replace in most cases. As always, make note of and remember the wiring connections when replacing these electrical components.

Is Your Fan or Your Compressor Bad?

If after you check these electrical items your AC still doesn't blow out air, or it blows only at certain speeds, your fan motor may be bad. If your AC blows but only hot air comes out, your compressor may be bad. Sometimes—not necessarily—a fan or compressor smokes or leaks oil when it goes bad.

A compressor that is working should turn on audibly and feel warm to the touch. You can test a compressor with a clamp-on ammeter, if you can rent or borrow one. Check how many amps the compressor is drawing. If it draws much more current than the amp rating written on the unit or on a nearby plate, the compressor is toast.

You May Be Able to Rebuild or Replace Your Fan Motor

Oiling your fan motor, as shown in Part 2 of this article below, will help it run more easily. If your AC fan motor is slow to start even after oiling, or needs a nudge to get it going, or only runs at certain speeds, or doesn't run at all, it will need to be rebuilt or replaced.

Fan motors come in two types: with exposed bearings which may be lubricated easily or with sleeved bearings (see the last photo in the article). The first type of fan motor may be rebuilt fairly cheaply and will last for many more years. But not so a sleeved-bearing AC fan motor.

Unlike fan motors with bearings, a fan motor with sleeves cannot be rebuilt economically, and must be replaced with a new one if it goes bad.

If your AC unit seems to be in pretty good shape otherwise, you can order a new AC fan motor to fit your particular unit. There are many sizes and models to choose from. Check the numbers on your old motor. By looking at pictures and descriptions on Amazon you may be able to identify a universal motor that will fit your unit.

Replacement of the AC fan motor is a simple job requiring only a few tools. If the electrical connection to the motor isnt a simple plug-in, mark down the colors of the wires before removing the old fan motor.

Test the new fan motor, before replacing the AC shroud, to check for proper alignment and fan clearance.

Removing and Replacing the Fan Motor

RV AC fan motor with retaining screws removed from AC chassis.  Your RV AC model may be different.
RV AC fan motor with retaining screws removed from AC chassis. Your RV AC model may be different.
Model and serial numbers on RV AC fan motor
Model and serial numbers on RV AC fan motor

A Bad Compressor Isn't Usually Worth Fixing

Compressor
Compressor

If, after you determine that the switches, capacitor, and relays are not at fault, the RV AC compressor fails to operate correctly and cool your air, it is usually better to just junk the unit and buy a new one.

Unless you have access to a used compressor and have the means to replace it and recharge the system yourself, it will likely be too expensive a repair. Under normal circumstances a compressor will last much longer than its warranty.

It May Be Simpler to Replace the Whole AC

If after investigating these possibilities you decide your old RV AC unit has enough problems to need replacing, please see my article on how to install a new rooftop RV AC unit. Replacing your old unit with a more efficient RV AC unit is a very simple and quick procedure you can do yourself.

Some Miscellaneous AC Problems and What May Cause Them

If your AC does run, but only with problems—overheating, dripping, being way too cold—you can address these problems too.

  • Overheating may be due to a simple failure to clean the coils—something I show you how to do in the second half of this article. When the coils are clean they can disperse excess heat into the air.
  • If water leaks into your unit and seems to come from the AC, investigate to see where it is coming from. The leak may come from the gasket between the unit and the roof; if so, it's easy to address. Tighten the bolts carefully, and if that doesn't work, replace the gasket.
  • Dripping from the unit itself may be caused by water condensing in the wrong place (in the pan under the air conditioner) instead of being evaporated by the fan. Such water buildup may be due to dirty coils, and if so, you can cure it by cleaning the coils.
  • If your unit blows very cold and builds up ice—and especially if it later stops cooling at all—it may be low on Freon. Sometimes you can see a visible oily residue around a Freon leak. You may be able to add Freon to your system yourself with a self-piercing valve.
  • If your motor is noisy, you can investigate the problem by taking the shroud (the cover) off the roof AC unit and seeing if everything is in place. The rubber shock absorbers on the compressor and fan may be interfering with the motion of the unit.

Part 2: Maintenance

Accessing the Condenser and Evaporator Coils to Clean Them

Removing the RV AC shroud retaining bolts
Removing the RV AC shroud retaining bolts

Maintenance gives your AC longer life and better efficiency. Roof air conditioning units on motorhomes are the same as ones used on other types of RV campers such as travel trailers and pop-up campers. These repair and maintenance procedures are identical for all these types of campers.

After a few seasons of use, it isn’t unusual for the AC unit to not cool the motorhome as quickly or as efficiently as it once did. Even if you clean the filters regularly, the evaporator and condenser coils will eventually become coated with dirt and grime, which inhibits airflow and cooling efficiency.

Before attempting any maintenance or repairs on the rooftop AC unit, be sure to switch off the electrical supply to the unit, either by tripping the breaker or by unplugging the motorhome from the electrical receptacle. You are now ready to remove the RV AC shroud (above) by unscrewing the four bolts securing it to the RV AC unit itself.

How To Clean the RV AC Coils

This coil is badly in need of cleaning
This coil is badly in need of cleaning
These coils are badly in need of cleaning too.
These coils are badly in need of cleaning too. | Source

After removing the AC shroud you will be able to see the evaporator and condenser coils on either end of the RV AC unit.

If they appear similar to those in the photos above then they need a thorough cleaning to allow unrestricted airflow through them.

Although regular household cleaners may clean the coils to a certain extent, AC coil cleaners made especially for the purpose, like ZEP Foaming Coil Cleaner, will remove the grime build-up much more efficiently and will not harm the coils themselves.

Follow the instructions carefully for the best results. A good wet/dry Shop Vac will help you clean up afterward and remove any excess cleaner or grime from the RV AC unit.

Use a coil fin comb to straighten any bent fins because they too will keep the airflow from moving through the AC coils efficiently.

These fin combs are very inexpensive and may be used many times in the future on both RV and home AC coil fins.

Air Conditioner Fin Comb
Air Conditioner Fin Comb

Straighten out those bent coil fins and increase the efficiency of your A/C unit.

 

Maintaining the AC Fan Motor

RV AC fan motor with a sleeved bearing.
RV AC fan motor with a sleeved bearing.

While the RV AC shroud is removed, it is a good time to service the fan motor and clean the fan itself. Whether your RV AC unit is made by Coleman, Carrier, Duotherm, or Dometic, it will have one fan motor which turns both the squirrel-cage fan and the heat exhausting fan.

This motor should be oiled at this time.

If your RV AC fan motor has regular bearings, there will be oiling ports at each end of the motor. It may be necessary to remove the metal sheeting over the top of the fan motor, plus a few sheet metal screws, to access the bearing oiling ports.

If no oil ports are evident, then your motor has sleeves instead of bearings. You may still oil the shaft at the point where the sleeves enter the fan motor housing. The oil will seep inside and help the fan motor last much longer.

Covering Your Motorhome AC Unit in the Off-Season

Your motorhome AC unit should give you many seasons of dependable operation if serviced annually. It's good to put a cover over the AC unit during the times when the motorhome is not in use.

These inexpensive RV AC covers protect the unit from moisture, extreme cold or hot temperatures, and debris from storms, birds, and insects. They will more than pay for their cost over time.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

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    • profile image

      Chrisr17 

      21 hours ago

      I’m testing now, but I believe the fan stops blowing after a while but the compressor doesn’t turn off. It would seem that if the sensor or themostat were bad it would affect the fan as well. I can turn the fan off manually but if I turn the front a/c to the off setting, the compressor doesn’t stop running. Only if I flip the breaker off. When I first replaced the control board, everything worked properly. I flipped the breaker and left it off for about an hour or so. It is cooling now and the fan is blowing but the compressor came on as soon as I flipped the breaker back on, before I turned the a/c on.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      22 hours ago from Southern Georgia

      Chris, hopefully it's simply a bad sensor, but other than that, I'm stumped! I'd be interested to know what you find out about this problem so I can assist others with a similar problem.

      Randy

    • profile image

      Chrisr17 

      22 hours ago

      Sorry I didn’t provide better info. The touchscreen I have controls my entire coach pretty much. All the lights, both ac units, furnace, slides, awning, water heater, tank heaters, and vent fans.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      22 hours ago from Southern Georgia

      Chris, I didn't realize you had two units controlled by a touchscreen. Still, something is apparently affecting the control board and there's not much left to replace on the electrical side.

      The screen has separate tempsettings for each unit and it's possible there's something screwy going on.

      Randy

    • profile image

      Chrisr17 

      22 hours ago

      Thanks for the reply. I’m not sure where the thermostat is located in my coach. I have front and rear units and both are controlled by a touchscreen near the door with sensors in the front and rear areas. If I replace the thermostat, will I need to replace the control board again as well?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      23 hours ago from Southern Georgia

      Chris, this is normally a control board issue, but since you've already replaced it then I suspect a bad thermostat as the issue.

      Randy

    • profile image

      Chrisr17 

      23 hours ago

      Randy, I have a Coleman Mach system. Noticed the compressor running but not the fan and it would not turn off with the thermostat switch. Had to flip the breaker. Replaced the control board assuming that the relay was bad. New control board worked for about 2 weeks and now the same issue. No cooling, and the compressor will not shut off unless I flip the breaker. Any ideas?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 days ago from Southern Georgia

      Roy, the stat sends signals to the control board. It could be either but make sure it's not the stat before replacing the control board.

      Randy

    • profile image

      Roy 

      2 days ago

      The stat is horribly inaccurate. For example, I can have it set to 79 degrees and the compressor will not kick off until 71 degrees. This season it seems to have gotten worse by far. I have never checked out the control board. Anything in particular I should know about it?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 days ago from Southern Georgia

      What is the problem, Roy?

      Randy

    • profile image

      Roy 

      2 days ago

      Randy, I have your basic, run of the mill, non digital or programmable Coleman Mach thermostat. I have about a 27' RV about ten years old. Nothing too fancy. The stat has a "Cool-Fan-Off-Heat" setting and a "Low-High-Low-High" Fan setting.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 days ago from Southern Georgia

      Brandon, have the capacitor(s) checked first. Any AC or electric motor repair can check and replace it for you. Cheap and easy to replace in most cases.

      Randy

    • profile image

      Brandon 

      2 days ago

      Question.

      What if ac was working then turned off for a few hours. Now I only got a single click noise and ac doesnt turn on?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 days ago from Southern Georgia

      Roy, are you sure it's the stat causing the issue? It may be the control board which receives the signals from the stat itself.

      Randy

    • profile image

      Roy 

      3 days ago

      Randy, I have your basic, run of the mill, non digital or programmable Coleman Mach thermostat. I have about a 27' RV about ten years old. Nothing too fancy. The stat has a "Cool-Fan-Off-Heat" setting and a "Low-High-Low-High" Fan setting.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 days ago from Southern Georgia

      Roy, I 'm not sure which stat you need to replace yours with as there are so many different models. Sorry!

      Randy

    • profile image

      Roy E. Spears 

      3 days ago

      Randy, my Coleman Mac thermostat is buggy and I want to replace it with a programable (digital) and more accurate one. I tried to replace it last summer with a digital Honeywell and learned not all thermostats are created equal, ending up putting the original one back on. Any suggestions on a replacement?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      5 days ago from Southern Georgia

      Neil, more than likely a bad capacitor. Cheap and easy to replace.

      Randy

    • profile image

      Neil P 

      6 days ago

      Randy, Great article! I have had a problem with my Coleman Mach twice now. Turned on the AC, fan runs but the compressor doesn't. After about 30 minutes the first time (last year) the compressor came on and the AC did fine for the rest of the trip. This month upon reaching the park, the same thing happened except the compressor did not start until about 12 hours later. Any Ideas?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      6 days ago from Southern Georgia

      Brad, the specs on your unit are well within the range for the compressor so apparently there's something else causing the issue. You may be correct in there being an issue with the GFIC.

      Randy

    • profile image

      B Foster 62 

      7 days ago

      Randy -

      Here is some information from the Airxcel sticker inside the unit. Let me know if this helps.

      Compr. LRA 63.0

      Compr. RLA 12.2

      Fan Motor FLA 3.4

      Minimum Circuit Amperage 18.6

      Maximum Overcurrent Protective Device Amperage 30

      Minimum Overcurrent Protective Device Amperage 20

      Thanks, Brad

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      7 days ago from Southern Georgia

      Brad, what amperage does your unit call for normally? |It should be listed somewhere on the unit near or on the compressor.

      Randy

    • profile image

      B Foster 62 

      7 days ago

      Randy,

      Thank you for your response.

      I was able to connect to a non-GFCI circuit and ran the compressor 3 times with the following results: start up amps = 22-28 amps, run amps = 7-9 amps. Compressor (A/C) seemed to run fine from this non-GFCI circuit.

      I also attempted to run from generator and the compressor would not start. It would draw about 14 amps, then the transfer switch would kick out and begin cycling on/off, trying to start the compressor. What is strange here is that if the compressor is bad, I would think the breaker would kick out instead of the transfer switch.

      What are your thoughts on the measurements?

      Should I chase anything else?

      The only other thing I'm thinking is that I have a ground fault somewhere in the A/C circuit, thus blowing the GFCI and generator is hesitating to connect? If you support this thought, where should I start?

      Thanks, Brad

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      7 days ago from Southern Georgia

      Linda, if you have a GEN/SHORE switch, be sure it's working correctly. Otherwise, check the amperage output on the generator.

      Randy

    • profile image

      Linda 

      7 days ago

      Randy, we have a dometic in our new 2019 leisure vans unity motorhome. The air conditioning works when we are plugged in but not when we have the generator on. Same with the microwave.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      7 days ago from Southern Georgia

      Brad, if you can borrow or rent a clamp on amp meter, you can see if the compressor is drawing more amps than normally required. It will be difficult to do if the power shuts off immediately though.

      All things seem to point to the compressor being bad anyway.

      Randy

    • profile image

      Brad 

      7 days ago

      Have a 2012 Coleman Mach 3 A/C unit that appears to have a bad compressor, but I'd like your thoughts.

      Here is where I'm at at so far:

      - Blower motor works fine in both high and low settings

      - Thermostat seems to work fine

      - All capacitors (3) tested good

      - To be sure, I changed both start and run capacitors for the compressor & no difference

      - On shore power: When compressor is actuated by thermostat, GFCI outlet from home 110V triggers and shuts off power to the coach

      - On generator: When compressor is actuated by thermostat, transfer switch flips back and forth until generator eventually shuts off

      - Resistance reading on the top of the compressor (without wires attached) are: Red to white 5.8 ohms, Red to black 5.2 ohms, and White to black 3.1 ohms

      Are there any other tests I can run to be sure its the compressor?

      Thanks, Brad

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      9 days ago from Southern Georgia

      Sara, more than likely the mistake burned out the control board in the AC. And the microwave may be toast as well.

      Randy

    • profile image

      Sara 

      9 days ago

      We moved to a new rv park when we left the one we were at to the other rv park we were on a 30 amp spot at old place and when we got to new place the rv got plugged in to a 50 amp plug and ever since then the AC and microwave hasnt work but the heater part of ac unit still works.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      10 days ago from Southern Georgia

      Mike, when you say you can hear the motor, do you mean the fan motor or the compressor? If it's the compressor running, then you may need a new fan capacitor.

      Randy

    • profile image

      Mike 

      10 days ago

      I have a 2001 cameo 5 th wheel and I’m having problems with the a/c. I turn it on and I can hear the motor but it’s not blowing any air through the vents.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      10 days ago from Southern Georgia

      Kevin, this is probably a thermostat or control board problem. Normally the thermostat send signals to the control board, but it may be the control board on your unit is sending a signal to the stat.

      Randy

    • profile image

      Kevin DeVries 

      10 days ago

      I have an older AC unit and the unit used to turn on and run and blow cold air for 20 minutes and then turn off for 20 minutes. When it turns off, it turns off the thermostat power and the display goes blank. If you left it alone, it would just keep cycling on and off like that. Now, it only runs for 2 minutes and then turns off for a couple hours.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      11 days ago from Southern Georgia

      Wendy, this more than likely a thermostat problem or a control board issue. Check the stat first.

      Randy

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      11 days ago from Southern Georgia

      John, this may be a thermostat or control board issue. Check the stat before replacing the control board.

      Randy

    • profile image

      wendy 

      11 days ago

      This is very basic I am sure, the thermostat shows the ac on and working, it displays 67, cool and fan sign on but nothing is happening in either unit. I feel like I am not hitting the right button. We usually just turn it on and it works. We are hooked to 50 amp and shows power coming in.

      flipped through all the buttons...nothing

    • profile image

      John 

      11 days ago

      I have a Coleman mach switch t stat to fan it turns on fan switch to cool and nothing no noise no fan. Any input would be greatly appreciated

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      11 days ago from Southern Georgia

      Manuel, yes the extra amperage just may be the cause of breaker tripping. When very hot, this little difference in amperage may be just enough to cause the overload.

      And yes, inadequate amperage from shore power could also play a part, especially if there's a huge draw from many other camper ACs running at one time. I'd let the manager of the park get this checked for you.

      Randy

    • profile image

      Manuel Pecos 

      11 days ago

      Hi Randy,

      I have my rv in a park and have a coleman that's tripping my breaker. All the capacitors, compressor and fan have been checked and are all reading proper ampage; with the exception of the fan. Specs listed are 3.4 and it's pulling 5. Would this be that big of a difference to trip my breaker or could it maybe be the transformer I'm pulling from at the park being overloaded? This issue only happens during the day when it's hot, at night it works fine and blows cold air. I've also cleaned the coils already. Please, advise cause this Texas heat is no joke. TY.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      12 days ago from Southern Georgia

      Ken, there may be a loose wire going from the thermostat to the control board in the unit itself. You'll need to remove the shroud to see.

      Randy

    • profile image

      Ken Furtado 

      12 days ago

      My front air works fine. Rear air has no 12 volt power to the Thermostat. Checked all fuses at the interior control panel all are fine. Not sure if I should head up to the roof and look up there at the A/C unit. Does the 12 v get to the thermostat from there?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      13 days ago from Southern Georgia

      Jodie, this sounds like either a thermostat or control board problem. Check the stat first before replacing the board.

      Randy

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      13 days ago from Southern Georgia

      Delbert, more than likely this is a bad compressor capacitor. Cheap and easy to replace.

      Randy

    • profile image

      Jodie Rodgers 

      13 days ago

      My ac runs, but it will shut off then come back on immediately. It will do this 2-3 times, then it will shut off and not come back on. To get it to come back on you have to turn the ac off and then turn it back on.If you switch the thermostat setting from auto to run, it works fine, but I don’t want to burn up my unit.

    • profile image

      Delbert Baker 

      13 days ago

      My motor home roof top air conditioner has worked fine, just until lately and now the unit blows nothing but hot air and I can smell a slight, hot wire odor. It seems the fan is fine, it blows a strong air supply.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      Ron, you should be able to find it online. Try Coleman's main site as I think they have a help crew.

      Randy

    • profile image

      Ron O 

      2 weeks ago

      Compressor overload protector is getting weak and shutting off my Coleman Mach unit. It is a Klixon part M3P2L. Where can I obtain this part?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      Justin, clean the coils and have the capacitors checked at any AC or electric motor repair shop.

      Randy

    • profile image

      Justin 

      2 weeks ago

      Switch it to ac and it takes a while then when running it doesn’t seem as cold as it used to be

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      dajobell, sounds like a bad compressor capacitor. Cheap and easy to replace.

      Randy

    • profile image

      dajobell 

      2 weeks ago

      Randy. The fan on the unit runs fine. The compressor sounds like it "wants to start". The compressor can be heard trying to turn on.The lights dim. Then turns off. It repeats this until unit is turned off.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      D Pearson, more than likely a capacitor going bad. About $25 or so and easy to replace.

      Randy

    • profile image

      D Pearson Sr 

      2 weeks ago

      Rodney getting RV ready for use. Turned on A/C. Left running for about 20 min. When returned inside smelled like we had electrical burn. A/C was cooling and fan was working. Turned unit off. Any thoughts on what might be happening?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      Rodney, more than likely this a bad capacitor. Cheap and easy to replace.

      Randy

    • profile image

      rodney scott 

      2 weeks ago

      went to store and come back and the ac is not working fan wont work either

      i do hear a click when i move the thermostat hotter or colder each direction

      i can move the fan with my finger

      by it is not doing anything

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      Kevin, to me this sounds like a bad control board. It may be the stat but I don't think so. I'd contact the maker/seller and see if they'd swap out the control board. It plugs in easily so there's no need for a serviceman. It should be under warranty as well.

      Randy

    • profile image

      Kevin 

      2 weeks ago

      Randy, I have a brand new unit and it shuts off after 2 cycles lasting about five minutes each. The Thermostat blinks with an E07 error. The manual says this is a high pressure sensor problem. How do I correct this? I tried resetting power input and restarting the unit a few times but cannot shake the error code after 2 cycles. Any thoughts?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      2 weeks ago from Southern Georgia

      Casey, you can check the capacitors yourself with a multimeter. Or you can take them to a local AC or electric motor repair shop and they can test and/or replace them for you.

      Randy

    • profile image

      CAsey 

      2 weeks ago

      Have a question, how do you know which Capacitor to get? We had someone come out and tell us it was the motor, replaced that and the fan runs, ac comes on, and it blows, but it is not blowing cold air. we are hoping a new Capacitor would fix it. but aren't sure what numbers or what to look for.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Jeanne, Can you tell if the compressor is coming on or not?. If not, it's probably a bad capacitor.

      Randy

    • profile image

      Jeanne Gurr 

      3 weeks ago

      A/c is running but not putting out much cold air

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Alex, first try cleaning the coils, especially the one behind the filter. If this coil gets clogged--as it normally does after years of use--it will cause the fan to not disperse the excess moisture into the air.

      It will also cause the compressor to overheat and shut down. Go to ACE hardware or Home depot and get some no-rinse coil cleaner and see it this helps.

      Randy

    • profile image

      alexander poe 

      3 weeks ago

      Great article, thank you! I'm having Travel Trailer A/C trouble. I'm unsure yet of the A/C model etc. Working on deadlines for work and have VERY limited time to figure this out. It's blowing cold, but not very hard. Just began making a squeeking noise. I noticed there is no water dripping from gutter outside. I switched thermostat from HIGH to LOW and it began blowing harder not softer. Also, water started dripping outside as usual...but only for a short time. Now there's no water dripping again. And moments ago it shut off all together. Can you tell me if this points to a common problem that can be fixed by myself? Thank you so much for your time!

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Bobby, probably a bad fan motor capacitor. Cheap and easy to replace.

      Randy

    • profile image

      Bobby 

      3 weeks ago

      My a/c is making noise but is not blowing

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Bojiboy, apparently you collapsed the ductwork when replacing the ceiling. It's easy to do with some ductwork as they are constructed with cheap materials.

      Sorry to be the bearer of bad tidings. You may be able to use a stick or some other object to spread the ducts back out by removing the duct covers.

      Randy

    • profile image

      Bojiboy 

      3 weeks ago

      My camper is a 2000, has a Duo Therm A/C unit. I just replaced the entire ceiling and insulation. I never unplugged any of the wires. Now it seems the intake return air blows, and the blower for the cold air is weaker. It still gets cold but it come staight down ond not thru the out vents. Suggestions?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Papa, this is either a thermostat or control board issue. Check the stat first before replacing the control board.

      Randy

    • profile image

      Papa Smurf 

      3 weeks ago

      I have an 85 model motorhome has two AC units my primary unit the compressor will not kick out it continuously runs any ideas

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      John, hopefully this may be a capacitor problem. If not, it may be either a thermostat or control board issue.

      Check the caps first before going any further and get back to me if you need further guidance.

      Randy

    • profile image

      john shill 

      3 weeks ago

      My RV has two ac units. the front one runs fine. the rear one gives me an E7 message on the Dometic thermostat. Can you help me on this to get the rear one running.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      BrainK--Have you checked the capacitors yet? Are you running off the generator? When you say "started the RV up" what do you mean?

      Randy

    • profile image

      Brain k 

      3 weeks ago

      Iv clean all Kohls ,,, iv change batteries,,,,iv change the little looks like telephone boxes ... iv change to a new thermostat inside on the wall .... here the dill I start them up and they may work or not.... when they do work they work good...my front one don't cool like the back and don't drip water... so I change the thermostat switch in the front roof air.... started working fine got down to 58 to 60 degrees .... thought had them fixed.... started Rv up and both of the Compressor kick out....I'm lots

      Running out of thing to check....last thing im going to do is run a wire to the thermostat on the wall to the air-conditioner and see if that work.... then I'm done may sell it and get a new one .... not really.... every body I talk to want to put a new one on there....but they work good when Compressor kicks I. And stays in....just seeing if u tell what else I can check

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Jessica, this is a strange problem. Unless the caps are weak, I can't imagine what the problems is.

      Randy

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      3 weeks ago from Southern Georgia

      Chris, there's a "contact author" icon at the top of the page where you can email me.

      Randy

    • profile image

      Jessica 

      3 weeks ago

      Love the article so maybe you might have insite on our issue. About 2 years ago we changed out our thermatse- we have a 2002 Alpine coach with Front & rear dometic duo-therm ac ducted. Normally we dry camp so if we need the AC we use the generate. once a year we camp at an RV park where we run the AC/s. We've gone to this RV place 3 times now and the last 2 years our AC make a click noise like relays are going on and off. We checked to make sure the shore power is good...ok there. we did notice when we turned up the tempature it wouldn't come on as much. Whats confusing is if we run the generate we don't have any clicking noise...any ideas where to trouble shoot?

    • profile image

      Chris 

      3 weeks ago

      Had a few questions on a thermostat operated AC unit. Is there a way to contact you a so I could send a few photos of some wiring+diagrams?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Kelly, the compressor may be going bad, but it's worth it to check the capacitors anyway before replacing the unit. You can check them with a multimeter set on ohms. A random number decreasing value means the cap is good. Any other steady number means the cap is bad.

      Randy

    • profile image

      Kelly 

      4 weeks ago

      We’re checking the capacitors in the morning. Can a bad capacitor make the compressor draw too many amps? My husband figured with the compressor getting so hot that it was probably going out.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Kelly, this may be a compressor drawing too many amps. Have you checked the capacitors yet?

      Randy

    • profile image

      Kelly 

      4 weeks ago

      The AC blows cold and the unit trips the breaker after the compressor kicks on and off a couple of times. The coils are clean. WE noticed the compressor becomes hot enough that you can’t leave your hand on it. Any suggestions?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Joyce, more than likely the old stat isn't capable with the new AC because the only other option is replacing the control board in the Dometic. As it's a new model I suspect the thermostat is the culprit.

      Randy

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Kristen, if you have replaced the capacitors already, you may have a bad motor. Normally, if you can start the fan by hand then it's usually a bad capacitor, but we can rule that out as you've already replaced them.

      Any kind of light oil will work if you can get access to both motor sleeves.

      Randy

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Shelly, I suspect the generator isn't supplying enough amps to run the AC. This will cause the compressor to overheat and trip off the generator breaker.

      Rent or borrow a larger generator and see if I'm right. If the AC runs okay on shore power then that's another indication of low amps from the GEN.

      Randy

    • profile image

      Joyce Myer 

      4 weeks ago

      We had a Coleman Mach roof top air conditioner on our travel trailer. We recently replaced it witha Dometic. Thr air conditioner runs cold. It wi not turn off unless we manually turn it off from the circuit breaker. We are still using our Colenam Mach wall thermostat

    • profile image

      kristen 

      4 weeks ago

      hi! great article. thanks for the info! i'm confused about my ac. the fan won't start, and the ac just hums. if i spin the internal fan by hand from inside the rv, it will start up, but it squeaks a bit, and seems to possiby be slightly loose? i replaced the fan and motor capacitor, but same problem. for financial reasons, i'm hoping it's not the motor! i don't see ports for oil, and all i have on me is my truck oil. could i use that or should i go buy a different kind? thanks for any help you may be able to offer! :)

    • profile image

      Shelley Bonang 

      4 weeks ago

      We have a Mach 3+ A/C, recently it started tripping the generator breaker ( generator is 3400 watts big enough to run the A/C). We checked the compressor and was really hot to touch. We cleaned the coils, and tested the run capacitor and was fine. We tried the A/C again and seemed to run longer but when i adjusted the temperature asking for cooler air, it tripped the generator again. We are planning a two week vacation and the RV dealers won't be able to look at the trailer until late August. I nee help? Also would a PTCR help??

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Gil, unless the thermostat is bad this sounds like a low Freon charge. When the system has a leak the unit will ice up right before the Freon runs completely out.

      Randy

    • profile image

      Gil 3 

      4 weeks ago

      I have 2 2018 model Airxcel 48000 Ac units on my fifth wheel. Today the bedroom Ac started blowing softer and not maintaining temperature. I cleaned the filters and I cleaned the condenser i can see from the outside of the case on top of the RV. Just now I removed the filters again and looked up into the AC unit. I see I assume is a condenser radiator. It’s frozen over. I felt the air blowing in was very soft and now I see why. What causes this to freeze over? The rv tech wants $300 to come out so I would like to make sure this isn’t a repairable item. I’ve shut off the air and it is thawing, water dripping down out of the ac as I write.

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Mary Kay, check and or replace the capacitors first.

      Randy

    • profile image

      Mary kay 

      4 weeks ago

      My ac starts but flips the breakers in my shop. I traded the breaker switch last night it worked. Come home from work no ac. I

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Ash, they are similar to RV ACs, but I'm not familiar with their inner workings. Meaning I don't know if they work like an auto AC or not. Sorry.

      Randy

    • profile image

      Ash 

      4 weeks ago

      Hi

      Do you fix the ac in shuttles it is look like RV ac unit

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Cathy, a weak capacitor could cause a clicking noise in either the fan motor or compressor on start up.

      Randy

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Edgar, you may have a control board problem if the capacitor doesn't do the job.

      Randy

    • profile image

      Cathy Carlton 

      4 weeks ago

      Randy you said to test the capacitor. Would the capacitor make noise if it is going bad? My unit still runs while it is making that noise. It happens sometimes at startup and sometimes in the middle of the run cycle then the noise stops but my ac dose not stop until it reaches the temp.

    • profile image

      Edgar 

      4 weeks ago

      My a/c unit don't start l have new capacitor its no working e worst working Perfect lm the capacitor blow l put new capacitor its its not working electric going to the conpresor

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Carlos, apparently the generator is not providing the volts/ amperage to run the system.

      Randy

    • profile image

      carlos 

      4 weeks ago

      I turn the generator on first. I wait the customary 20 seconds and the power comes on. Then I turn my AC on, the fan comes on first, then when the compressor comes on the generator RPMs drop almost to nothing and the AC stops. But, if I hook it to the 30 amp outlet in the RV park it works perfectly. Would could the problem be?

    • Randy Godwin profile imageAUTHOR

      Randy Godwin 

      4 weeks ago from Southern Georgia

      Try grounding the wire, Brett. It may or may not make a difference.

      Randy

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