How to Clean the Battery Cooling Fan in a 2004-2009 Toyota Prius

Updated on January 7, 2018
My 2nd generation Toyota Prius, 2008 model year.
My 2nd generation Toyota Prius, 2008 model year. | Source

Why Clean the Battery Fan?

The battery cooling fan does its job hidden behind the interior trim panels in the rear cargo space of the Prius. Toyota doesn't require or suggest cleaning this fan as part of a regular maintenance schedule, and most people won't ever need to. However, if you regularly carry furry friends in the back seat, you might want to do so every 60,000 miles or sooner.

The cooling fan intake vent—in the rear-right of the Prius—can suck in loose hair and debris, clogging the fins inside the blower fan that feeds cabin air into the battery pack to keep it cool. If allowed to accumulate, over time, the fan will eventually be completely clogged, preventing the fan from cooling the battery effectively. This can produce error codes related to the battery pack overheating, reduce performance—the multiple ECUs (electronic control units) will limit battery usage for driving or regenerative braking—and lead to premature failure from being subjected to extreme temperatures.

Tools You Will Need

To access the cooling fan, you will need the following tools to remove the interior pieces and components:

  • 10 mm socket
  • 12 mm socket
  • A pair of good hands

I also recommend an upholstery pin removal tool that slides under the head of the push pin. It allows you to pop it out much more easily than trying to pull on the material around it.

Step-by-Step Directions for Removing the Battery Cooling Fan

1. Remove the rear seat cushion at the back.

The seat cushion is held in place by two of these loops, one on each side, that pull out easily.
The seat cushion is held in place by two of these loops, one on each side, that pull out easily. | Source

2. Remove the bolt and pull out the intake grill assembly.

This is a 12 mm hex bolt.
This is a 12 mm hex bolt. | Source

3. Fold the seats down.

Seats folded down.
Seats folded down. | Source

4. Remove the first bolt securing the right rear trim panel.

This is a 10 mm bolt. You'll need a 10 mm socket with an extension to access it.
This is a 10 mm bolt. You'll need a 10 mm socket with an extension to access it. | Source

5. Remove the second bolt securing the the right rear trim panel.

Remove this bolt with a 10 mm socket.
Remove this bolt with a 10 mm socket. | Source

6. Remove the third bolt and luggage strap hook.

This is another 10 mm bolt.
This is another 10 mm bolt. | Source

7. Remove this part of the hatch trim.

It pulls out easily with both hands and pops out.
It pulls out easily with both hands and pops out. | Source

8. Remove the left luggage hook point.

It is secured with a 10 mm bolt.
It is secured with a 10 mm bolt. | Source

9. Remove the right luggage hook point.

Same as the other one on the left.
Same as the other one on the left. | Source

10. Pull up the carpet panel covering the battery.

Battery now exposed.
Battery now exposed. | Source

11. Remove the push pins at the bottom of the right rear interior panel.

Remove upholstery push pin and pull out right-rear interior panel.
Remove upholstery push pin and pull out right-rear interior panel. | Source

12. Pull the right rear trim panel out.

It is held in place with more upholstery push pins.
It is held in place with more upholstery push pins. | Source

13. Remove the intake duct.

First, remove the push pin holding the end of intake duct to battery cooling fan (white). I highly recommended using an upholstery pin removal tool.
First, remove the push pin holding the end of intake duct to battery cooling fan (white). I highly recommended using an upholstery pin removal tool. | Source
Gently pull on the ducting assembly to pop out this push pin and remove the intake duct to gain access to one of three bolts securing the fan.
Gently pull on the ducting assembly to pop out this push pin and remove the intake duct to gain access to one of three bolts securing the fan. | Source

14. Remove the three 10 mm bolts securing the cooling fan.

First bolt on the bottom.
First bolt on the bottom. | Source
Second bolt on the top.
Second bolt on the top. | Source
Third bolt can only be accessed after removing the intake duct.
Third bolt can only be accessed after removing the intake duct. | Source

15. Detach the fan's control plug (but don't disconnect).

Squeeze the clips on the opposite side (hidden in picture) and push down.
Squeeze the clips on the opposite side (hidden in picture) and push down. | Source

16. Remove the fan's power plug.

Squeeze the clip on the plug and pull out gently.
Squeeze the clip on the plug and pull out gently. | Source

17. Clean the Cooling Fan

The battery fan removed and disconnected.
The battery fan removed and disconnected. | Source
A deeper look inside the cooling fan. There's some buildup of dirt on the fins, but nothing that will prevent it from doing its job.
A deeper look inside the cooling fan. There's some buildup of dirt on the fins, but nothing that will prevent it from doing its job. | Source

If the fan has hair or lint in it, try using a vacuum cleaner with a crevice tool to suck it out. For finer, stickier grime that won't vacuum off easily, use an old toothbrush or pipe cleaner to loosen and then vacuum it out.

When re-assembling, make sure you get the power plug for the fan reconnected before bolting everything back in or else your Prius will throw a diagnostic trouble code related to the battery cooling fan not working (well duh) and a master warning triangle light on the dash. This won't harm your Prius—it's just letting you know something isn't right.

The code can be cleared by disconnecting the negative terminal on the car battery for a few seconds before reconnecting. Keep in mind that if you need to do this, you'll lose any radio presets as well as mileage driven and average MPG information. You will also have to re-initialize the auto roll down feature on the driver window. Hold the control button down until the window is fully down and then hold it up until the window is all the way up.

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    • jesimpki profile image
      Author

      jesimpki 5 months ago from Radford, VA

      Hey Brian! Glad to hear it helped!

    • profile image

      Brian 5 months ago

      Just wanted to give a shout out for this article. My dog kept throwing hair at our battery fan and it finally let us know.

      Followed the instructions, problem solved. Thank you!

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