heater problems
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heater problems
I have a 88 corvette with electronic heat and ac control and it seems as though the heat does not shut off and it get real hot in the cabinet while driving I heard about a valve that controls the heat to the cabin but mike does not have that valve in the line thats under the ant ideas
Le Mans Master
Joined: Jul 2007
Posts: 5,356
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From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
The heat is not controlled by a valve. There is a door that closes over the heater core when heat is not needed. I have the same problem. I installed a shut-off valve in the bottom hose to the heater core (5/8") and open and close it when needed. When it comes time to replace the heater core I will repair the door mechanism. The core will have to be replaced eventually and I only want to do the job once.
Another option is to remove the blower resistors and force the door closed but that is a real PITA and the moving air will open the door in a day or two.
Another option is to remove the blower resistors and force the door closed but that is a real PITA and the moving air will open the door in a day or two.
Last edited by pkazsr; May 13, 2012 at 08:34 PM. Reason: another thought
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
There was a water valve in the heater lines that bypassed the heater core when in A/C mode. It was eliminated in the late '80s sometime.
The temperature in the cabin is controlled by the HVAC programmer, which controls the temperature door motor. I will bet that you have burned resistors or bad solder connections on your HVAC programmer PC board. The HVAC programmer is mounted on the firewall right above your right foot when you're sitting in the driver's seat. Check this thread I wrote for tons of info on the HVAC programmer. There's a pic in there that shows the resistors that get hot (they are part of the motor control circuit):
http://forums.corvetteforum.com/c4-t...schematic.html
The temperature in the cabin is controlled by the HVAC programmer, which controls the temperature door motor. I will bet that you have burned resistors or bad solder connections on your HVAC programmer PC board. The HVAC programmer is mounted on the firewall right above your right foot when you're sitting in the driver's seat. Check this thread I wrote for tons of info on the HVAC programmer. There's a pic in there that shows the resistors that get hot (they are part of the motor control circuit):
http://forums.corvetteforum.com/c4-t...schematic.html
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Bad Programmer vs plugged up core. When the Core plugs up, coolant flows over the top, but not through it. I'd check out the Temp Door position first. Remove the Module on the left side of the Evaporator Case and look inside to see the door. Have someone operate the controls to make sure it opens and shuts. Assuming it does - meaning the Programmer is working - try flushing the heater core.
