A/C & Heater Door Problem
Thread Starter
Heel & Toe
Joined: Jul 2007
Posts: 16
Likes: 0
A/C & Heater Door Problem
96 vette with auto climate control, has no heat coming out of the vent even I set it up to 90 degree. I check the heater control valve it is open and clean. Then I remove the fan control module on the top of the evaporator box, there I found out that the door is barely moving when I cycle the temperature up and down. I have to close manually to get the heat coming out or open it for cold air. Could it be the door motor??? Please help me to pin point the problems and how to fix it.....pictures are great for a home mechanic like me. Thank you very much!
Le Mans Master
Joined: Jul 2007
Posts: 5,356
Likes: 2
From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
If these links work they will be alot of help
the blower module removed
Image: http://temp.corvetteforum.net/c4/89p...vaccontrol.jpg
you are looking down into the box to try to see the mix door
Image: http://temp.corvetteforum.net/c4/89p...ngdooropen.jpg
Image: http://temp.corvetteforum.net/c4/89p...//hvacdoor.jpg
In the above pics, the casing is removed, don't remove your casing.
On the inside of the car is another door link. Here are some pics, but keep in mind te entire dash was removed. You would have to try to see it from "underneath" the angle I show in my pic.
Image: http://temp.corvetteforum.net/c4/89p...vacrod_001.jpg
Image: http://temp.corvetteforum.net/c4/89p...vacrod_003.jpg
Try to see if one of the 2 plastic links is broken or if the core is plugged up.
If those fail, we can see if your controller has a loose solder conection on 2 of it's resistors.
Let us know what you find.
the blower module removed
Image: http://temp.corvetteforum.net/c4/89p...vaccontrol.jpg
you are looking down into the box to try to see the mix door
Image: http://temp.corvetteforum.net/c4/89p...ngdooropen.jpg
Image: http://temp.corvetteforum.net/c4/89p...//hvacdoor.jpg
In the above pics, the casing is removed, don't remove your casing.
On the inside of the car is another door link. Here are some pics, but keep in mind te entire dash was removed. You would have to try to see it from "underneath" the angle I show in my pic.
Image: http://temp.corvetteforum.net/c4/89p...vacrod_001.jpg
Image: http://temp.corvetteforum.net/c4/89p...vacrod_003.jpg
Try to see if one of the 2 plastic links is broken or if the core is plugged up.
If those fail, we can see if your controller has a loose solder conection on 2 of it's resistors.
Let us know what you find.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Pkazar – Nice pictures and good information. But I question the motor and configuration of the 94 – 96 cars. I believe your information is for the 88 that uses the clips.
I believe the 96 uses a direct shaft from door into the reduction motor. The motor is beneath the evaporator box and can be viewed from inside the car after a few panels are removed from the passenger side. I think the motor is held up by just a few screws.
You can also check the position of the door by using the diagnostic mode of the C68 controller. By going into the diagnostic mode by pressing the up-down arrows at the same time and going to test 12 and 36 you can check the position (counts) of the motor and door. Press the center button for the reading. You can run the temp up and down and see if anything is changing.
From the number of wires going to the motor I have seen, I assume the resolver (feed back unit) is incorporated in the motor also. This would feed back to the controller for position indication.
I am out of town this week and have done all this from memory. I hope I have not made an error for I do not have my books with me to verify this information.
I believe the 96 uses a direct shaft from door into the reduction motor. The motor is beneath the evaporator box and can be viewed from inside the car after a few panels are removed from the passenger side. I think the motor is held up by just a few screws.
You can also check the position of the door by using the diagnostic mode of the C68 controller. By going into the diagnostic mode by pressing the up-down arrows at the same time and going to test 12 and 36 you can check the position (counts) of the motor and door. Press the center button for the reading. You can run the temp up and down and see if anything is changing.
From the number of wires going to the motor I have seen, I assume the resolver (feed back unit) is incorporated in the motor also. This would feed back to the controller for position indication.
I am out of town this week and have done all this from memory. I hope I have not made an error for I do not have my books with me to verify this information.
Last edited by pcolt94; Oct 28, 2008 at 09:31 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Later Years are direct, gear driven doors, and that gear can strip which keeps the door from moving. And if you can push on it and close it, you probably have that problem. Door position, as spit out from the Controls doesn't always mean that the door has moved to it's commanded position. Calculation is based on how long the motor runs - it doesn't mean the door moved. I'd remove the passenger side hush panel and remove the motor which will let you see the gear. Someone around here found the gear, but I don't know where.
Pro
Joined: Mar 2008
Posts: 579
Likes: 2
From: High Bridge New Jersey
96 C4 is known
96 vette with auto climate control, has no heat coming out of the vent even I set it up to 90 degree. I check the heater control valve it is open and clean. Then I remove the fan control module on the top of the evaporator box, there I found out that the door is barely moving when I cycle the temperature up and down. I have to close manually to get the heat coming out or open it for cold air. Could it be the door motor??? Please help me to pin point the problems and how to fix it.....pictures are great for a home mechanic like me. Thank you very much!
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Vacuum controls the HVAC vent doors - it has nothing to do with the Temp Door which is run by an electric motor (electronic air) or a cable (manual air). And it continues to work that way, even on '09's.
Le Mans Master
Joined: Jul 2007
Posts: 5,356
Likes: 2
From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
Pkazar – Nice pictures and good information. But I question the motor and configuration of the 94 – 96 cars. I believe your information is for the 88 that uses the clips.
I believe the 96 uses a direct shaft from door into the reduction motor. The motor is beneath the evaporator box and can be viewed from inside the car after a few panels are removed from the passenger side. I think the motor is held up by just a few screws.
You can also check the position of the door by using the diagnostic mode of the C68 controller. By going into the diagnostic mode by pressing the up-down arrows at the same time and going to test 34 and 36 you can check the position (counts) of the motor and door. Press the center button for the reading. You can run the temp up and down and see if anything is changing.
From the number of wires going to the motor I have seen, I assume the resolver (feed back unit) is incorporated in the motor also. This would feed back to the controller for position indication.
I am out of town this week and have done all this from memory. I hope I have not made an error for I do not have my books with me to verify this information.
I believe the 96 uses a direct shaft from door into the reduction motor. The motor is beneath the evaporator box and can be viewed from inside the car after a few panels are removed from the passenger side. I think the motor is held up by just a few screws.
You can also check the position of the door by using the diagnostic mode of the C68 controller. By going into the diagnostic mode by pressing the up-down arrows at the same time and going to test 34 and 36 you can check the position (counts) of the motor and door. Press the center button for the reading. You can run the temp up and down and see if anything is changing.
From the number of wires going to the motor I have seen, I assume the resolver (feed back unit) is incorporated in the motor also. This would feed back to the controller for position indication.
I am out of town this week and have done all this from memory. I hope I have not made an error for I do not have my books with me to verify this information.
