I own a pontiac grand prix 2000 with a 3.8 motor. I cannot get my A/C to work on any speeds but 5. I have replaced the resistor and, recently, the blower motor. Would the only thing left to replace be the speed dial on the dashboard? My resistor has been rusted out for some time because I have a windshield leak that leaked onto the resistor. I have fixed the leak since I replaced the resistor.
Upon replacing the resistor the first time, I was able to use speeds 1-4 again. A few days after replacing the resistor, the speeds 1-4 went out again. This is when I had the idea to replace the blower motor since it was squealing.
Could the problem possibly be the resistor again or the dial speed control for the A/C?
Any advise is much appreciated.
Thanks
If the resistor fixed the problem the first time, I would try replacing it again, especially if you fixed the window leak after the first resistor was replaced as the continued leaking may have killed it again.
The problem could be in the fan speed selector switch. When there’s a problem it snowballs like a line of dominos.
Failing blower motor draws more current which makes the resistor run hotter which in turn causes the fan switch to run hotter, etc.
It could very well be that the failing blower motor has knocked the resistor out again and the fan switch is fine. This should be easy to test with a VOM or test light.
“This should be easy to test with a VOM or test light.”
Right - you don’t have to guess about it. Get a meter or light and test the power. Do you get 12v at the resistor on all fan switch settings? Then the switch is probably fine. Back probe or jumper the fan connector, and see what you get for each fan position. If 12V makes it to the resistor, but then not to the the fan, then your new resistor got taken out by your old noisy fan.
Well my brother has a 1998 grand prix that is having the same issue. At times the car works on 1-4. Others works on only 5. It varies… I will test the voltage on the HVAC switch and get back with you.
Is it also possible that it is the relay switch between the blower motor and the HVAC Panel?
There’s a high speed blower motor relay in the blower circuit. This relay switches the voltage to go thru either the blower motor resistor for the low blower speeds, or switches the voltage directly to the blower motor for the high speed.
This relay might be causing the no lower blower speeds problem.
Tester
I purchased a fan blower relay switch, but cannot seem to figure out where it is located…
I attached a picture of the relay.