please help
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Joined: Jul 2009
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please help
I have a big problem that i need someone who knows c4s to give me an answer.I have a 88 corvette that has electronic heat and ac control.If I drive longer than 15 or 20 min. the heat that radiates from under the dash is almost unbearable.The heater control is off but it feels like the heat is still.Does anyone know what I can do thanks in adance
Le Mans Master
Joined: Aug 2005
Posts: 7,392
Likes: 216
From: Merritt Island, FL
A word of advice: If you put some information in the thread title, other than "please help", other forum members will know what it is that you're asking about, and may be more likely to open your thread to try to help you.
Now, what you are describing could be due to a faulty diverter valve (supposed to shunt hot coolant away from the heater core unless heat is requested at the control head, or it could be a faulty blend door actuator.
If full cold is selected, and there's a lot of heat coming from under the dash (but not the vents), I suspect that the diverter valve is either broken, or its vacuum supply is compromised.
I don't have an early C4 with the diverter valve (later cars didn't use them), so my help ends there. However, you can trace your coolant hoses from the front of the engine compartment, to the area near the blower box, passenger side firewall, there should be a plastic device with hoses coming into and out of it.
Now, what you are describing could be due to a faulty diverter valve (supposed to shunt hot coolant away from the heater core unless heat is requested at the control head, or it could be a faulty blend door actuator.
If full cold is selected, and there's a lot of heat coming from under the dash (but not the vents), I suspect that the diverter valve is either broken, or its vacuum supply is compromised.
I don't have an early C4 with the diverter valve (later cars didn't use them), so my help ends there. However, you can trace your coolant hoses from the front of the engine compartment, to the area near the blower box, passenger side firewall, there should be a plastic device with hoses coming into and out of it.
Melting Slicks
Joined: Jan 2002
Posts: 2,531
Likes: 35
From: Lecanto Florida
First, the valve shuts off the hot water supply to the cabin. There's slide mechanism that goes into and out of the valve you can make it work by hand when the valve breaks. Pull or push that slide valve to see if it shuts the water off on yours.
The valve can't be bought separately. You have to buy about 2 feet of pipes (2) and the valve attached. Either Mid America or Eckler's has it in their catalog.
My mechanic found a different kind of valve that did the same thing and just cut into the pipes and attached the valve. All that and cheaper than buying an after market replacement piece.
The valve can't be bought separately. You have to buy about 2 feet of pipes (2) and the valve attached. Either Mid America or Eckler's has it in their catalog.
My mechanic found a different kind of valve that did the same thing and just cut into the pipes and attached the valve. All that and cheaper than buying an after market replacement piece.
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Brett Foote
Racer
Joined: Sep 2007
Posts: 375
Likes: 18
From: Lawrenceville Georgia
I assume that there is no control of the temp setting?
First thing I would check is the air mix door in the HVAC box underhood for proper movement. This door can be observed by removing the blower high speed relay/module. This sits on top of the HVAC and has two plugs attached, and has 3 7mm screws in it.
Remove this and with a flash light you can look into the opening and see the door. With engine running, move the temp button up and down and door should move. Closed is for less heat, open is for more heat.
Joel
First thing I would check is the air mix door in the HVAC box underhood for proper movement. This door can be observed by removing the blower high speed relay/module. This sits on top of the HVAC and has two plugs attached, and has 3 7mm screws in it.
Remove this and with a flash light you can look into the opening and see the door. With engine running, move the temp button up and down and door should move. Closed is for less heat, open is for more heat.
Joel
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I just answered this in another thread, but here goes...
The temperature in the cabin is controlled by the temperature door. The HVAC programmer controls the door position by sending voltage to a motor. MANY times the resistors on the HVAC programmer either burn or the solder connections go bad from the heat. Here's a thread I wrote that describes all this, with lots of pictures:
http://forums.corvetteforum.com/c4-t...schematic.html
The temperature in the cabin is controlled by the temperature door. The HVAC programmer controls the door position by sending voltage to a motor. MANY times the resistors on the HVAC programmer either burn or the solder connections go bad from the heat. Here's a thread I wrote that describes all this, with lots of pictures:
http://forums.corvetteforum.com/c4-t...schematic.html
