Hey everybody,
I'm quite new to this forum but figured I'd have better luck here than dropping coin on a mechanics opinion. I would much rather fix it myself, if at all possible. I have owned this car with these problems since I purchased it, but with the inevitable winter approaching I need help! Its a 2004 by the way.
-my low beams receive no power however, my high beams receive constant power
-the high beams dim slightly when power windows are in use
-the heat nor the a/c work at all even though the dash control lights turn on when I turn them
I replaced the blower motor and resistor. I've also checked and replaced bad fuses and bad relays. There was a crappy after market radio in it, although I'm not sure if that could effect my current issues. Any help would be greatly appreciated (probably going to have to see a mechanic though right?) haha Thanks guys

-Nick

 

Not certain on this but possible causes of your issues could be

Bad ground for the headlights
Bad ignition switch causing the fan and a/c to not work, yes this could be the culprit as it does effect the cruise and a/c when the ignition switch is bad, it will take a few seconds or up to 15 minutes for them to engage after starting and driving the car, and periodic flashing of cruise on the dash display

Your mutli function switch could need replacing, it may not be disengaging the high beam, this is a common problem with our cars

There is also the chance that whomever replaced your stock radio mixed up some wires in behind the dash that could be causing a ground issue behind the scenes.

I am guessing on this and hopefully someone else can chime in that may have experienced your exact issues, I will try and do some research and see if I can get anymore information for you

By the way welcome to the forum

 

Here are some links that may be of assistance

This one points out the multifunction switch being possible culprit for headlights

Pontiac Grand Prix Questions - Front headlights won't work - CarGurus



this is from another post on our forum

"OK guys we have been fixed! After removing the steering wheel cover, exposing the multi-function switch, I found that you would have to remove the steering wheel to remove the mutli switch. Too much work for me. So we took it to our trusted mechanic and $600 later the switch, with a 42" wiring harness attached, was replaced and all is good. I have the old switch and may try and rebuild it at a later time. When/if that happens ill update this post. Dealer wanted $525 for the switch and my mechanic found it for $381. Sorry guys wish I could have posted a cheaper fix or told you how to fix without buying parts, but this is reality.
Good luck to all and thanks to all who replied with help. This is a great forum!!

Zod642"


Here is a write up on an 01 impala, which is similar to our car and it also points to the multi function switch

2001 Chevrolet Impala, No Low Beam Headlights


you can buy a new switch on RockAuto Parts Catalog the part cost $125 here is a link to what it looks like outside of the steering column

More Information for DORMAN 2330862

 

Another possibility is the Body Control Module (BCM). I believe all those systems run through the BCM. It's possible it could be bad.

 

And now for the heat and air, not sure if these will help but maybe you will see something you missed?

8 Steps to Fix Your Automotive Heater Like a Pro (Pictures)

http://repairpal.com/blower-motor-resistor-521


Chevrolet Monte Carlo Heat and AC Problems - Car Forums at Edmunds.com



and I hate to say this, but another cause could be your bcm, this causes some weird electrical issues when it goes bad, I believe a dealer can test it as I think you need access to a tech 2 scanner, and you can't buy these parts used from a junker, they need to be new and programmed to the car by the vin I believe.