Heater problem

[air1jpg]

I have a 96 LT1 with the automatic climate control. I am getting little heat while the temp setting is at 85 or lower and the fan stays on low. If I set the temp setting to 90 (all the way up), The fan goes to high and I just about get blasted out of the car with hot air. Could this be a sensor or heat control valve problem? I figure it could not be the heater core since I do get heat. I am going to try the control unit diags I found on some other posts I found on this site. Any other suggestions would be appreciated! Thank you.

 

[air1jpg]

The control unit diag mode did not show any codes but "00" which is normal.

 

[gmjunkie]

There is a plastic clip on the blend door that has probably broken!! There is a thread and photos here somewhere in C4 section,but I can't find it!!

 

[air1jpg]

blend door

Thanks for the reply. Where is the blend door? Is it behind the dash? Is it the door that is opened by an electric motor that lets the heat get to the vents? ;help

 

[jmccloud]

Hot air

If you're getting truly 'hot' air with the setting at 90F, it's likely a failed sensor. In fact, that's the diagnostic technique. The outside one is in front of the right front tire, up near the radiator shroud and inside the wheel well. I don't know where the inside one is in a Corvette.
I've had 2 GM cars with your symptoms and it was the outside temp sensor in both cases. Replacement is easy once you locate it. About $40 (oughta be $4).
Good luck

 

[air1jpg]

Did you get a outside temp reading when you had problems with your outside temp sensor? My control unit still shows a outside temp which I think was close to the correct outside temp at the time.

 

[jmccloud]

Outside temp

The outside temp displayed was in error in both cars. That fooled the controller unless the control was set to 90.
The inside sensor may be off. My son had a new Grand Prix with this problem. Dealer replaced the sensor but I don't know where it is. If you don't have a Helms, I'd be glad to try and look up the location for you.

 

[air1jpg]

Jmcloud,
I would appreciate it if you would look that up for me. Thank you.

 

[jmccloud]

Inside air temp sensor

The sensor (according to my '95 FSM) is located on top of the heater housing above the passenger side knee panel and bolster and it has two short electrical leads with a connector attached. To access it, remove the passenger kick panel then the bolster. Make sure to disconnect the battery as the air bag is just above this area. The thermistor, aspirator and breather tube are located above the passenger's knees and below the a/c outlet. The sensor has an aspirator attachment (breather tube) that conveys air from the heater plenum to the thermistor temperature sensor. So the aspirator or breather tube may be plugged with dust and not getting air across the sensor. Or, the sensor itself may be bad.
There are two tables of resistance versus temperature values in the FSM for the inside and outside thermistor temperature sensors. In summary either sensor should read about 9kOhms at freezing, 5.5k at 50F, 3k at 70F, and 1.5K at 100F. There's also a long troubleshooting section for evaluating the HVAC programmer and connections for shorts and opens. But if there's a short or open, you should see DTCodes.
Good luck and call back if you need more.

 

[vigman]

I had a similar problem

I'll find my post of the A/C temp motor ( servo)

Vig~