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Troubleshooting Hyundai Air Conditioning Problems

Just a guy with an aptitude for many things mechanical, electrical, and electronic who has been building and fixing things for 40+ years.

The A/C blew hot air when in stop-and-go traffic.

The A/C blew hot air when in stop-and-go traffic.

We live in Arizona and needless to say, during the summer it tends to get a little warm; it's a dry heat they say. Whatever ... it's hot!

My wife had been complaining that the A/C in "her" car, a 2005 Hyundai Santa Fe, didn't seem to be working as well as it used to. We didn't have a chance to get it in the shop before we left on our trip to Flagstaff for the Fourth of July weekend, but we figured it'd be okay until we got back. Wouldn't you know it, though; shortly after we started out, we agreed the A/C wasn't working very well at all. It worked reasonably well if we were traveling 40 mph or more, but when we slowed down or stopped, it started blowing warm air.

Since the chances of a traffic jam on I-17 between Phoenix and Flagstaff on holiday weekend seemed pretty high, we decided to go back home, transfer everything from the Santa Fe to our truck, and use that for the weekend. We'd worry about the A/C when we got back.

Cool forest near Flagstaff, a great place to not think about the A/C.

Cool forest near Flagstaff, a great place to not think about the A/C.

The Mechanic Thought the A/C Was Working Well

The weekend went well and we had a lot of fun, but it ended, as usual. So that meant I had to do something about the A/C.

I took it to a shop, and they checked out the A/C and told me everything was working well except that it was half a pound low on refrigerant. Since the system capacity is just 1.3 lbs, half a pound low is significant. For $160 and some pocket change they evacuated the system to get out all the air and water, and refilled it with refrigerant, oil, and a dye to help find future leaks.

It worked better after that but it still wasn't 100%. At stop lights, it would still blow warm air. Once we got moving again, it would blow cool air again after a couple minutes. Apparently, everything was NOT working well.

I'm not a professional mechanic but I'm pretty handy. I do most of the maintenance and repair on our cars, home, appliances, etc. Although I have almost zero experience with A/C, I decided to look at it myself. Five minutes of research on the Internet revealed that the most common reason for A/C blowing warm air at idle is a condenser fan that's not working.

hyundai-santa-fe-air-conditioning-troubleshooting

I Looked Under the Hood

It took some looking to find the condenser and condenser fan. The condenser is located in front of the radiator on the driver's side, the fan is located behind the radiator. The condenser looks similar to a small radiator.

I started the car, turned on the A/C and never saw the fan run. That made me wonder why the engine didn't overheat. More research revealed that there is also a fan located in front of the radiator on the passenger side; this is the radiator fan. This one was running.

Safety Warning

Both A/C fans are electric. On some cars these fans can start at any time, even when the car is turned off, so keep your fingers and anything else you value away from them. Disconnect the battery or the fan connector if you need to work directly on the fan.

Checking Voltages With a Multimeter

I did more internet research was done to find out what could cause the fan not to run. Most of what I found was related to fuses under the dash, and fuses, fusible links, and relays under the hood.

The first thing I decided to check was voltage at the fan. If there's voltage at the fan that pretty much narrows it down to a bad fan.

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I could't get the fan connector apart, so I checked voltage by sticking two pins in the wires of the fan harness. No voltage. I checked all fuses, fusible links, and relays and all tested good. I pulled the connector off of the temperature sensor, which should start the fan if everything else is good. No go: the fan just sat there.

Now I was stumped. There was not much else to look at except wiring and the thought of troubleshooting wiring didn't appeal to me at all.

The Problem Was a Melted Fan Connector

It bothered me that the fan connector wouldn't come apart, so I decided to get that apart even if I broke it in the process. I figured if it broke, I would splice it. I pried one side with a screwdriver and heard a slight snap. Did the same to the other side and also heard a snap. After that, it slid apart easily.

I checked voltage at the supply side of the connector and read 12 volts. Now I was getting somewhere! I had voltage on one side of the connector but not the other! Further inspection revealed that the inside of the plug was melted, possibly due to a bad connection that caused excessive resistance.

Put current through resistance and it creates heat. Put enough current through enough resistance and it creates too much heat. Many plastics don't like heat.

Warning

Keep your fingers away from the fans. Disconnect the battery or the fan connector if you need to work directly on the fan.

How I Did My Repair

1. I bought some weatherproof butt connectors from Checker. If you do this repair yourself, you will also want to have on hand a crimping tool and some electrical tape or heat-shrink.

2. I removed the condenser fan relay so that no power would be at the connector.

The relay that you will need to remove is under this cover.

The relay that you will need to remove is under this cover.

The condenser fan relay was removed temporarily to disconnect power to the fan.

The condenser fan relay was removed temporarily to disconnect power to the fan.

3. I cut the leads off of both sides of the connector. I spliced the now connector-less wires with the butt connectors.

4. With the power disconnected, I checked the fan to make sure it turned freely. It did!

5. I let it idle for 10 to 15 minutes, and the condenser fan ran continuously and the A/C blew cold the entire time.

6. Satisfied with my repair, I wrapped the spliced wire tight with electrical tape and zip-tied it to the bracket where the connector was located.

The completed repair

The completed repair

I Was Not the First to Find a Melted Connector in a Hyundai A/C

At the time, nowhere on the Internet did I see this connector mentioned as a possible problem. The outside of it had looked fine; it was just the inside that was melted.

But, the Internet is now saying in a number of places that connectors in air conditioners, including in other Hyundai models like the Sonata, melt and cause this problem of no cooling when the car is not running fast.

Justin Peters, who made the video below, had a similar problem on the same car: a failed connector leading to the condenser fan, on his 2005 Hyundai Santa Fe. He fixed it by picking apart the interior of the connector. He explains that a loose connection can melt and fail entirely. The loose connection causes higher resistance, and causes more power to be dissipated across the connection, which ends up as heat and melts the wire.

In a Kia Spectra (and the video author says the Hyundai Elantra is similar), a a similar connector in a different place (near the passenger-side foot well) melted and caused the A/C's temperature sensor to fail.

I learned a long time ago that when troubleshooting, you should never say, "That can't be the problem." Entertain all possibilities from the complex to the extremely simple. In this case it was a simple component that nobody told me was prone to fail ... but it did.

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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