Haven’t driven the 06 for a few days. Started it up and the fan did not work in the front. No matter the fan speed. Turned it off for a bit then back in and the fan came back on. Was working fine for ten seconds or so then started to have erratic fan speed before completely turning off.

I removed the cabin filter and moved the fan with my hand and it moves freely, doesn’t feel like it’s sticking. I feel this is an electrical issue. I havent touched anything electrical in the vehicle for a while. Last time I drove it the fan speeds worked fine.

The digital display works fine and the rear fans work perfectly fine.

I tried to record the erratic fan speed but by that time the fan was no longer spinning.

I went back and started the car again, the fan worked then died. This time I have a video:



Any thoughts?

 

From what I’ve read around online seems like the most likely culprit is the relay or the resistor, since the motor spins up and mechanically works.

I understand the resistor is under the dashboard, but which relay governs the blower motor?

 

The heater fan motor relay is under the hood on the driver's side. It uses a 50A fuse.
There is also a 7.5A Heater 2 fuse that is for the fan controller.

The fan controller (the GX doesn't use a simple resistor) is mounted on the fan housing right by the motor itself.
p/n is 87165-13010 and is pricey at $275

If you want to test it with a voltmeter:
Pin 1: WHT/BLK - ground
Pin 2: LT GRN/BLK - control signal from the A/C ECU
Pin 3: GRN/ORG - 12V
Pin 4: WHT/BLU - goes to pin 1 of the motor

It's rare for the controller to go bad but it does happen.
I would first change the 7.5A fuse and make sure it seats firmly.
Also look for wiring damage by rodents.
I think it's unlikely the 50A fuse is bad, but remove it and check with an ohmmeter.

The control signal on Pin 2 is a pulse-width modulated one. You probably won't be able to tell much using a voltmeter unless it can display frequency.
The duty cycle for each speed is:
Off - 0%
Lo - 26%
1 - 40%
2 - 53%
3 - 70%
Hi - 100%

Hope this helps
Chip H.

 

Thanks Chip. For the 50A fuse, I looked into the fuse box and there are several fuses tied to the AC or Heater. Do you mean the 50A fuse that’s in slot 4 according to the fuse map?

Does the fact that the motor works fine upon engine startup help diagnose the problem more clearly. I’ve read some stuff that it can’t be the resistor because it doesn’t work at all. I’ve also read some stuff where if the fan just completely doesn’t work, it’s the blower fan itself that should be replaced.

im not super confident in my electrical diagnosis skills and would rather just change mechanical parts.

 

I don't know about slot 4. It's square, red, and next to the 140A fuse on the row furthest away from the battery.

The fact that the blower runs at all (per your video) says that it isn't the problem.

And again, the fan controller is not just a simple resistor. There's a microprocessor in there.

Chip H.

 

I think I found the issue. I checked the fuses and they were all good.

I took the motor out and what I believe is the ground wire in the relay is corroded.



I haven’t had a chance to clean it up and test it but will do that tomorrow. Not sure how the corrosion got there, but when I took the fan out there was some moisture in there. Maybe condensation from the AC.

 

I did some more testing and took more stuff apart. I pulled the resistor and it’s clearly the problem.




The farthest screw was also very corroded. Not sure where the moisture is coming from since everything else underneath looked really good. Any ideas?

In terms the resistor, I know generally the consensus is to replace with OEM parts, but anyone have luck with other manufacturers?

 

For this, OEM only. There was a post a long time ago where they replaced it with a clone and it didn't go well.

No idea on the water.

Chip H.

 

Ordered OEM part from PartSouq for 160CAD including shipping.