No headlights with HVAC fans on, my grand prix [Archive] - Forum


View Full Version : No headlights with HVAC fans on, my grand prix

01-15-2007, 06:23 PM
This isn't grand am related, but I know there are a lot of peeps on this forum that also own W-bodies like me so I figured I'd ask. I'm checking on clubGP also to see if anyone's run into this problem before, because I'd like to know what I'm looking for before I dig into things.

It's a '97 grand prix gt and the headlights turn off when I turn the hvac fan switch on, but the fans don't turn on either. The only fan speed I have is 5, and when that is on the headlights come back on. Any other fan speed the switch is at, the fans go off and there is a loud click somewhere behind the left side of the dash and the headlights go out. Turn the hvac switch to off and there's a click again (sounds like a relay kinda) and the lights come back on.

The lights only go out if operating during auto night time mode also. If I turn the headlights on manually, they stay on when I turn on the hvac, but I still hear the click and the fans still don't work. I just started doing this 3 days ago. I'm pretty sure the fan speed resistor is fine because it was bad and I replaced it with the new kind when I bought the car two years ago. That and yesterday it went back to working like normal again and I still had all fan speeds, but then today it's back to fubar'd again. Any ideas?

btw I have a viper 560vx remote start/alarm on the car. I had it installed back in october though and everything's been fine since then. Could it have something to do with this problem though? I don't know why it would have any connection to the hvac at all, or even the headlights really. It only flashes the parking lamps when arming/disarming, but during remote start it has a timer and the lights go on/off every few seconds until you get in the car and put the key in, turn it to on, and press the brake pedal to cancel the timer. Usually after pressing the brake pedal all the lights and hvac would turn off for a second then come back on and work normally. Thats the only connection I can see.

01-16-2007, 07:07 AM
I don't know for sure what the problem is but I wouldn't just assume that the blower motor resistor is good since you installed one 2 years ago. I have had them last as little as 1 year or less.

01-16-2007, 10:16 AM
The headlights should have a thermal overload instead of a fuse. That might be what you hear clicking. It should be in the fuse box.

In my '96 N body, the wires went through the firewall with a connector by the left side hood hinge. I had a couple weak connections that would open when the rear window defrost and the brakes were on. I would lose the radio too.

I ran a drill bit through the bad terminals and replaced them with new wires that were spliced on both sides of the connector.

Good luck and I hope the info helps.

01-16-2007, 09:22 PM
No, clicking is definitely inside the left side of the dash and there are no fuse panels there. The inside fuse panel is next to the glove box and the engine compartment one is on the passenger side.

Tjc, the fan speed resistor is definitely good. I haven't had one go bad after having replaced it with the new design. Also during the day time when the auto headlights aren't working, the fans work like normal. If the resistor had gone bad they wouldn't. It has to be connected to the lights somehow.

01-18-2007, 05:01 PM
Just trying to help... and with what you are saying I agree with you.

01-18-2007, 10:41 PM
maybe a short to voltage in the wires

i hope my assumption that you have a service manual or online manual for your GP is correct

01-19-2007, 11:01 AM
I have a manual for my mom's '98 intrigue which is pretty much the same thing.

Anyway, I think I got the problem nailed down. The guys on said that similar problems can be attributed to dirty contacts on the main ignition switch. I guess they are known for this. They gave me several options for fixing it, and I just need to wait until I can get my car in the garage to check it out.