So the rear vents that serve the second row of seats in my 2005 Honda Pilot stopped working a few months back. Â I didn’t really think much of it, since my car is rarely used for long trips, but still installed a Blackbox My Car camera in case of accidents. Until recently, when Brynn got carsick on a long drive cuz there wasn’t enough air back there.
So I did some research online and discovered that it’s actually a common problem. It was listed in a service bulletin of the original 2003 model but sporadically has plagued all other first-generation model years up to 2008 as well.
The problem seems to be caused by a blown thermal protection fuse (or thermal cutoff) in the transistor that drives the rear blower. It’s either a low-quality cutoff or airflow is severely restricted (in turn, causing the transistor to overheat).
So I decided to check it out. I popped off the driver’s side panel of the center console. In this picture, the air intake screen is on the left and the green plug on the right is connected to the transistor assembly.
My air intake screen was definitely clogged up. Yuck.
Next, I removed the wire plug from the transistor assembly. There’s a little tab in the lower right to release the transistor, and it’ll rotate a quarter turn clockwise and come out.
Now at this point, you can buy a replacement transistor assembly from a dealer. I saw quotes of $120 or so on some message boards. (Using Google I found it for as cheap as $85 + shipping).
Or if you’re like me, you’ll try to just fix the one you have. So pop off the cover to expose the circuit board.
I didn’t do a good job taking pictures, but the blue arrows point to the leads of the thermal cutoff, which is actually on the other side of the circuit board. You have to remove the heat sink (the big silver thing) by removing three screws holding it to expose the actual thermal cutoff.
I ordered a new 115C 2A/250VAC thermal cutoff for $0.78 plus $2.18 shipping and waited a couple days for it to arrive.
In my haste I forgot to take a before picture, but I unsoldered the blown cutoff and soldered in the new one.
I reassembled everything in the reverse order and installed the fixed transistor back into the Pilot.  I also vacuumed the intake screen. See how much cleaner the intake screen is?  Big difference.
Turned the car on, and nice fresh air was blasting out the rear vents again. Yay!
My next project is going to be replacing some of the burnt out back lights in my climate controls.
[Updated 11/30 – Fixed Digi-Key link]