Hello if there is anyone out there that can help it would save me hundreds of dollars. I have a 2001 pontiac bonneville sle w/ 114,000 miles.

The PROBLEM is the electronic heater controls turn off and on whille driving intermittently.
The heater temp display screen will then turn black and you can't use any buttons while this is happening the blower turns on high in defrost mode usually blowing cold air(with a black screen still and no function of buttons).

I replaced air blower resistor ($150)and the whole display screen/unit ($100) still no fix? What is the part i need to replace?
Im going to pick it up tonight from the auto shop which could not figure out the problem. they said take it to dealer maybe and maybe its the bcm??the dealer has a $95 diag. fee!!
please help asap this is my winter/work car and i cant even use the AIR controls.
THANKS

Do you happen to have an aftermarket head unit installed?

Sometimes when people put aftermarket stuff in, they have to chop away at the back of the hole to accommodate the deeper head unit. Directly behind the opening is the printed circuit cable which supplies power to the heater controls. If this cable is damaged in anyway, I can see how it would cause the heater controls to malfunction.

Even if you don't have an aftermarket head unit in now, it might have had one in the past. I'd pull the radio out and check things out.

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

thanks for getting back to me so soon.
I do have an aftermarket head unit in my bonny. but i put it in 3 years ago, the problem just started 2 weeks ago.i did not cut any thing when installing harness . i bought the right ribbon harness from the pro. audio store ($100 later). but i will take a look,
also the shop i just had it at already looked there and at my fuses today.
thanks