Question about Blinking HVAC on 98 Buick

Hey guys this question is going to be for the GM guys on the board.

I have an old 98 Lesabre, and it runs and drives great. When I first got it I had to do the Vacuum line mod on the programmer to get the HVAC to blow out the face vents. That was the best $1.60 and 30 min I spent on a car :slight_smile:

That mod still works and was done about 1.5 years ago, the ENTIRE time i have owned the car the temp blinks when I start the car, but the HVAC has always worked fine so I paid no attention to it. That is until 3 weeks ago when I had to replace my intake manifold. I disconnected the battery without turning the system to “off”. I have been doing a bunch of reading online, and it seems I may have thrown the system’s sync off by doing this.

Right now my problem is this, colder air coming from the pass side then the driver’s side. When I start the car it will seem synched for a few seconds, then it will start blinking and both vents will go FULL COLD, eventually it brings the temp back up the d-side gets hotter than the p-side. I have done the following:

  • gone through AT LEAST 50 on/off cycles
  • Removed the 9c fuse to try to reset
  • Pulled down the glove box door and watched both the upper and lower blend doors go through there whole range of movement (which they do)
  • Tried to re-sync by pushing the temp full hot, then full cold a few times in a row.

Besides getting this scanned by a tech 2, which is my last resort, is there anything else I can do?? Did I miss anything??

Thanks again

Is this a computer controlled system with dual zone climate controls? I don’t know a thing about them but I figured I’d post & at least your Q gets a bump.

I do know that many GMs have a calibration procedure for the HVAC system that you can probably find online & give it a shot. This is the kind of thing that the car does itself & it just involves the right combination of button pushing & knob turning & whatnot. I have an Olds & found mine in Autozone’s online repair info. If you don’t find it there a general internet search might turn it up if you use the term “calibration.”

So even if that doesn’t help your post got a bump.