89 , ac no heat
Thread Starter
Heel & Toe
Joined: Sep 2020
Posts: 22
Likes: 3
89 , ac no heat
I had my new to me 89 convert out today and with it being 6 c , 38 f , I put the HVAC control to heat. I only got cold air which makes me think the acuator must be stuck on the ac side ? I have lower running temp on the guage at 165 F than my other C4 did which ran at 220 F on average. I also have lower oil pressure at 270 average than my other car which was usually 375-450. Anyone else experianceing similar sypmtoms ? I did do a search on the HVAC issue here but the results were pretty much 100% C5 related.
Last edited by 1956meteor; Oct 25, 2020 at 08:10 PM.
Drifting
Joined: Aug 2002
Posts: 1,775
Likes: 125
From: Birmingham AL
Yes, typical issue for the 89. I’ve had 2 with the same exact problem. Pull controller board from above gas pedal. Note positions of vacuum lines, not all colors match. Reheat solder joints on corner of board. 2 big resistors on one corner if I recall. That should fix it. Worked for me on 2 different cars.
Melting Slicks
Joined: Jan 2014
Posts: 2,187
Likes: 381
From: Lunenburg MA
You can pull the fan control module off the engine side of the heater/ac box and see the door position. It could be the two resistors mentioned above or a bad/disconnected door motor, or a bad controller.
Melting Slicks
Joined: May 2019
Posts: 3,217
Likes: 1,392
From: Mid-Atlantic
2025 C4 of the Year Finalist - Unmodified
2023 C4 of the Year Finalist - Unmodified
2022 C4 of the Year Finalist - Unmodified
2021 C4 of the Year - Unmodified Finalist
I'd replace the thermostat and burp it. But previous advice is simple to do so can't hurt to check that, too. If you're getting cold air, as in ac quality cold air, it's probably the contoller.
I had the same problem, turned out that in my case the thermostat was 160 degree and wasn't letting the car get hot enough. I wan't getting ac quality cold air, though, just regular non-heated air.
I swapped it out for a higher temp thermostat, burped it, and now the heat kicks.
The old thermostat tested good.
I had the same problem, turned out that in my case the thermostat was 160 degree and wasn't letting the car get hot enough. I wan't getting ac quality cold air, though, just regular non-heated air.
I swapped it out for a higher temp thermostat, burped it, and now the heat kicks.
The old thermostat tested good.
Last edited by Natty C; Oct 27, 2020 at 08:02 AM.
Drifting
Joined: Feb 2008
Posts: 1,537
Likes: 177
From: NE Ohio
2024 C4 of the Year Finalist - Unmodified
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Thread Starter
Heel & Toe
Joined: Sep 2020
Posts: 22
Likes: 3
Thanks 65Z01 and kenmohr. I am in Northern Ontario and winter is approaching fast . I will likely just take the car up the street , fill it with premium and put in the garage until spring. I have saved all your replies. thanks gents.