I have a 1991 Pontiac Grand Am, whose AC/Heater motor will not run at times when I try to turn it on. This happens especially on a cold morning when I need to run the defrost mode. It does not run on any setting either. It has 3 speeds none of which will work.
At other times it works fine. Such as now in the middle of the day on this beautifully sunny Oct afternoon, when I do not need it!
Any clues? Is there a sticky relay somewhere? If so where do I find it.
I have managed to locate the relay. In the attached photo it is the leftmost one attached to the bracket on the firewall. This “C” shaped bracket has 4 relays on it. If anybody can identify the other three I would appreciate it for future use.
I identified the correct one by placing my finger on all four of them while some else turned the blower on and off from the inside using the blower speed control knob. The relay exhibiting the strongest click was the one. I confirmed it by disconnecting the cable harness from it, and the blower switch no longer turned. Reconnecting the harness allowed the blower to work again.
My suspicions are I have a sticky relay that does not work when it is cold. I am waiting till I can diagnose more about this problem on a cold morning. Though I do not look forward to working in the cold, I look forward to solving the problem.
Hope this information helps somebody else.
The next time your blower motor doesn’t run, tap on the blower motor with the handle of a screwdriver or a stick. If the motor comes on, the problem is the motor. I don’t think your problem is the relay as it is only used for high speed setting and bypasses the resistor pack.
I think you just have a worn and sluggish motor. They will do that when cold, especially GM. Don’t think its the relay at all. That motor is right out in the open and you should be able to just replace it in about 15 minutes and $30. So either live with it or just replace it. Back in the 80’s I had taken them apart and lubed the bearings but it requires drilling the rivets and doesn’t last long.