Hey all, having some trouble with my blower motor. ‘91 NA. When I slide the fan speed control, I hear a relay click on, and an additional relay click on max speed. Allegedly, the AC worked before it sat for 2 years but I have no way to verify that. I’ve seen people replace the power resistor and transistor and guides on how to do that, just wondering if that should be my next step here. Are there any connectors I can jump to verify that those are my issue? I know I should look at the fsm, Its just a little intimidating and I haven’t yet 😅. I’ve probed around with a multimeter and my fuses are all good and I have 12v one of the connectors plugging into it (whichever one I could see from the passenger footwell)

 

Are you saying that the blower motor only works on high speed, despite where you move the fan speed ****?

 

Hey there! Initially, when I made the original post, the answer to that question was no. The blower motor did not spin at all regardless of the speed setting. I heard relays click on and off, but no air. However, yesterday I had some time and went ahead and worked on it a little bit. I probed around a little and ended up jumping the red/yellow wire to the blue/white wire as that should send 12v directly to the motor. Nothing happened.

That had me thinking there was something up with the blower motor itself. I went ahead and pulled it out since it was only 3 bolts. I then put a couple alligator leads in the connector and powered it straight off the battery and hooray! It spun!

After that, just for fun and because I was running out of time, I went ahead and plugged the fan back in. This time, when I moved the speed selector to the highest setting, it turned on! The first couple of times to turn it on I had to kind of jiggle the selector in between max high and just before it, but I have left it on max the past couple of times I’ve turned on the car and it comes on. However, it still doesn’t work on any other speed but max high. After reading some other threads, and because I can hear a the relay for the intermittent speeds click, I think I need to test my power resistor. I just haven’t had a chance to get back in there yet.

I’m currently working on refilling the ac system. I wasn’t getting any cold air and the compressor wasn’t kicking on so I hooked up my gauges and I had about 70 psi on the low side and 50 on the high side. Something wasn’t right there. I wonder if the previous owner (who’s impeccable work I’ve had the pleasure of fixing other places on this car ) tried to fill it with r12 or possibly even r134 when there was a bunch of air in the system. I went ahead and evacuated it and drew a vaccum last night and it’s been holding steady. I’m gonna jump the compressor to make sure that works before I source and use r12 to make sure I don’t waste it. It’s 96 degrees and humid here so now that I have air blowing I’d love for it to be cold.

 

So, as far as the fan is concerned, it sounds like there are a couple of problems. Problem 1 is that it sounds like the blower motor might need some cleaning. These motors are old and have a lot of brush dust buildup. Opening it up and cleaning out the brush dust would help with the no-start. On the lack of variable speed control, the first test would be to disconnect the blower motor and use a multimeter to check voltage at that plug. The blower controls regulate speed by varying voltage to the blower motor transistor, which is located on the blower motor assembly. If you have no low-speed voltage, unplug at the transistor/regulator, and test the terminals there. There should be a 12v, a variable line, and a line out to the motor. Do these tests after cleaning the blower motor.

There is a good thread on here for R152. I followed it and have been very happy with the results.