98 Riv climate control issues.

Hi everyone,

I'm somewhat new here, I was a member in the past but do not remember what my username was. I lost my previous Riv 7 years ago due to tornado damage and flooding. I recently picked up another one for $400 with 240K on it, runs like a champ but I have one issue I hope someone can help me with.

My climate control display only has a small CF displaying on it, none of the buttons work, and the fan blows on high as soon as the car is turned on. It started last week after I had to replace my 4 rear subframe mounts and bushings. I had to torch the bolts due to rust, driver's side bolts came out with minimal effort, one of the passenger bolts came out with more torching, and the other I had to get red hot before it would budge. In that process the insulation and carpet backing on the passenger side melted right above both bolts so I am thinking I melted a wire or fried the HVAC module. I unplugged the module "brain" and turned the car on, still does the same thing.

Does anyone have a wiring diagram for the hvac "brain"? Has anyone else had this problem and solved it? Any help would be greatly appreciated! Thanks!

SteveInMN wrote:

Hi everyone,

I'm somewhat new here, I was a member in the past but do not remember what my username was. I lost my previous Riv 7 years ago due to tornado damage and flooding. I recently picked up another one for $400 with 240K on it, runs like a champ but I have one issue I hope someone can help me with.

My climate control display only has a small CF displaying on it, none of the buttons work, and the fan blows on high as soon as the car is turned on. It started last week after I had to replace my 4 rear subframe mounts and bushings. I had to torch the bolts due to rust, driver's side bolts came out with minimal effort, one of the passenger bolts came out with more torching, and the other I had to get red hot before it would budge. In that process the insulation and carpet backing on the passenger side melted right above both bolts so I am thinking I melted a wire or fried the HVAC module. I unplugged the module "brain" and turned the car on, still does the same thing.

Does anyone have a wiring diagram for the hvac "brain"? Has anyone else had this problem and solved it? Any help would be greatly appreciated! Thanks!

No schematic here BUT I did successfully repair my HVAC head unit - my hobby is electronics, though. If you are an electronics hobbyist or know someone who is, it's not unlikely that you could disassemble the unit and make simple repairs.

That said, what I would do would be to get a factory manual and check the wiring, then get a replacement unit from a junkyard or from one of the ethical subset of junkyard vendors on eBay or $75-$175, just search "1998 Buick Riviera Heater Control" there are a bunch of them. The reason to have the manual -- it may be the programmer that's dead not the heater control, it is a separate box. $50 or so off eBay and about $170 off RockAuto.com, you'll want the FSM to do diagnosis.