75 heater trouble shooting
Thread Starter
Race Director
Joined: Jan 2007
Posts: 10,684
Likes: 696
From: Danville Illinois
2025 Corvette of the Year Finalist - Modified
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75 heater trouble shooting
Is there a trouble shooting/diagnostic guide for heat/air for a 75, the heater works but i don't feel the heat coming out of the vents i select, same for the air.
The car heats but i think its only coming from the floor vents, i don't think the top dash vents are working. With air on it does seem like the dash vents do work.
If i just put it on vent nothing is happening.
After owning the car for 37 years you would think i would have figured it out by now.
Any guidance would be appreciated
The car heats but i think its only coming from the floor vents, i don't think the top dash vents are working. With air on it does seem like the dash vents do work.
If i just put it on vent nothing is happening.
After owning the car for 37 years you would think i would have figured it out by now.
Any guidance would be appreciated
Last edited by Mod75; May 7, 2012 at 10:42 PM.
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
Its probably a vacuum problem with the heater/ac control system in the console, OR, the vacuum moduals are out that change the venting behind the dash. Maybe Willcox Corvette has something on this?? in their service help.
Pro
Joined: Jun 2001
Posts: 528
Likes: 147
From: Palmyra NY
I am in the process of rebuilding mine right now. When I pulled it apart, there was a nest so large in the main heater box that the actuator could not open/close. I pulled out what looked like a basketball made of carpet insulation, walnut shells and little brown sprinkles...and voila...it works again.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Do you have the assembly instruction manual (AIM)? The AIM has a couple of pages on HVAC diagnostics. Sounds like your selector door is not moving and is not allowing changes to the air flow (floor to defrost, floor to vents, etc.)
Thread Starter
Race Director
Joined: Jan 2007
Posts: 10,684
Likes: 696
From: Danville Illinois
2025 Corvette of the Year Finalist - Modified
2024 C3 of the Year Winner - Modified
2021 C3 of the Year Finalist - Modified
2019 C3 of Year Finalist (appearance mods)
Thanks to all for the input
