Air Conditioning Control Problem

[Futures Passed]

I've tried looking this up a while back, but I didn't find anything that helped, and it doesn't seem to be a common problem. My air conditioning works, but the dial doesn't on settings 1 through 4. On setting 5 (the highest), the air conditioning kicks in.

Additionally, the front lights turn off on settings 2 through 4 when increasing the level, turn back on when it gets to 5, and stay on when you turn it back to "off".

I've plugged in my OBD II laptop program, but I didn't get anything related to this (only something exhaust related). If I fix this and the catalytic converter, the car will have no problems for the first time in years.


Vehicle: 2001 Pontiac Grand Prix SE 3100, no air conditioning modifications.

[bszopi]

My guess would be the blower motor resistor. RockAuto has several different ones. It may have something to do with the lights if its shorted out for the 2-4 selections.

[Futures Passed]

My auto mechanic friend and my dad were saying it was likely a bad ground. I think I checked the relays (if those are the cube things in the under-hood fuse box) a few months ago and changing them out didn't fix it. I'm not sure what I'd do with the lights, though. I don't suppose just buying a new set would fix that, would it? They're already yellowed and full of humidity anyway.

Thanks for the quick response!

[Z3500]

Blower motor resistor FTW

Auto zone:

http://www.autozone.com/autozone/parts/2001-Pontiac-Grand-Prix/A-C-Heater-Blower-Motor-Resistor/_/N-jflklZ91tag?filterByKeyWord=blower+motor+resistor&fromString=search

[pocket-rocket]

Blower motor resistor #3.

It's unanimous

If it were a ground the blower motor would not come on when on 5. The blower motor resistor is bad and is shorting out on 1-4 and that's why it's dimming the lights. The blower comes on when 5 is selected because the switch bypasses the blower motor resistor on 5.

[55trucker]

My son just went thru this nonsense with his '02 GTP.
The A/C started to cut out/not function, his headlights began to behave in an erratic manner.
The ignition switch module had failed. The car would start fine/run fine, but those accessories driven off it were affected.

[Futures Passed]

I had seen that part around a while back, but I wasn't sure if it got put in. I talked to my dad about it and he said he put the new one in and it worked for about 30 seconds. I'm not sure if I'm willing to buy another one if they last that long. If I do, I'll see if we got the wrong one first; Z3500's link had two kinds listed.

[55trucker]

Save your money....it's not the blower motor resistor.
It's the harness for the ignition switch.
See thread entry #27 & 28......

http://www.grandprixforums.net/key-stuck-ignition-lock-cylinder-2-7824.html

[Z3500]

The link I gave has two parts, by different manufacturers, but same application. Either will work.

I still say its the resistor, but it wont hurt to check your ignition first. And it should not burn out after 30 seconds.... never heard of that.

[Futures Passed]

I'll pass that on to the person doing the spending. Do you know where to get that part for the cheapest? I only ask since you said you recently went through that as well.

Thanks for the info, everyone! I'll post here once I fix the problem or get stuck again.

[55trucker]

^Well, I'm near Toronto, but on the US side I'd say Rockauto would be your least expensive location to get one. You can choose whichever brand suits you.