ZR-1 Net Registry Forums - View Single Post - C68 HVAC Programmer Compatibility for 1990

Axial · 11-01-2021

Update 2:

The diode turned to powder during extraction, making it impossible to identify via testing or inspection. Oof. Swapped it for one of the larger diodes in the kit, replaced the transistors, and skipped on the caps since the ones on there were not giving off any bad vibes. After installing it back into the car, it worked fine for about 20 minutes and then it began steadily degrading until it went back to the triple dashes.

Since I would've needed a new kit anyway, I sent the unit to Batee for a rebuild; he replaced the caps and the transistors, tested it, and signed off on it. I put it in my car and I get weird failure modes. At first it was doing weird mode changes all by itself, sometimes giving me a blinking light and sometimes not. I thought there might be a vacuum leak triggering states, so I took a dive under the plenum last week and fixed a bunch of loose connections. Now, after having done that, it's still failing but it's more consistent; it will give me a grace period when I start the car to select a mode, temperature, and fan speed and then it will stop responding to commands. I can still turn on the rear defroster and I can enter diagnostic mode from this state, but I can't change the HVAC settings until I turn the car off and then turn it back on.

Anybody encounter this before, where the HVAC effectively "freezes" its settings while driving the car and you can't alter then without shutting off ignition and restarting?

11-01-2021	#7
Axial Join Date: Aug 2021 Location: Manassas, VA Posts: 15	Re: C68 HVAC Programmer Compatibility for 1990 Update 2: The diode turned to powder during extraction, making it impossible to identify via testing or inspection. Oof. Swapped it for one of the larger diodes in the kit, replaced the transistors, and skipped on the caps since the ones on there were not giving off any bad vibes. After installing it back into the car, it worked fine for about 20 minutes and then it began steadily degrading until it went back to the triple dashes. Since I would've needed a new kit anyway, I sent the unit to Batee for a rebuild; he replaced the caps and the transistors, tested it, and signed off on it. I put it in my car and I get weird failure modes. At first it was doing weird mode changes all by itself, sometimes giving me a blinking light and sometimes not. I thought there might be a vacuum leak triggering states, so I took a dive under the plenum last week and fixed a bunch of loose connections. Now, after having done that, it's still failing but it's more consistent; it will give me a grace period when I start the car to select a mode, temperature, and fan speed and then it will stop responding to commands. I can still turn on the rear defroster and I can enter diagnostic mode from this state, but I can't change the HVAC settings until I turn the car off and then turn it back on. Anybody encounter this before, where the HVAC effectively "freezes" its settings while driving the car and you can't alter then without shutting off ignition and restarting? __________________ [B]1990 ZR-1, No. 729[/B]