I have a 1994 corvette with the c68 option and the a/c doesn't cool. I started out by checking pressures and the freon level since the car had been sitting for and extended amount of time. Every thing was ok there; the compressor works fine and the a/c line leaving the evaporator is cold as it should be, however, the temp inside is still hot. This led me to check the temperature actuator inside the car. I removed the lower knee bolster to observe the actuators actions to the control heads commands and it didn't move. I removed the actuator itself to see if the door was stuck and if it had free movement. The door moved easily with the twist of my fingers and with the car running cold air came out of the vents. I thought this was a dead ringer for a temp door actuator but when I installed the new one nothing changed. That means I have an input problem to the actuator. I checked the dtcs off of the control head by pressing the up and down arrows on the blower motor speed and then auto after it displayed 00. It then redisplayed 00 which i think means no dtc's in the system. Now I am baffled because there is no section in the service manual that says no cooling with no dtcs. The only idea I have to go with is that the hvac programmer is bad or the control head but which one is just guessing. Has anyone seen this before?

 

This is gonna take some effort....

Pull the control head out and check the wiring for continuity between it and the actuator motor. I'm betting open circuit between the two. You've definitely found the problem, now it's just a matter of finding out WHY. Post your results.

 

ever have mice in your car?
I fixed my eaten up vac lines and everything works great

 

I think its' a hvac programmer. This morning I took the connector off of the actuator to check the voltage being applied to the motor when the the temp is selected. When the temp is turned to 90 degrees I have -8 volts being applied to actuator when I change it to 60 degrees the voltage goes to zero. At about 72 is where it transition from -8 to zero which the outside temp currently. That make sense because the hvac programmer controls the actuator by changing powers and grounds.

 

I got a brand new programmer that been sitting on a shelf for 17 years at a dealership for $160.00. Hooked it up and it worked like a champ the A/C will run you out of it.

 

How much do you want for your old one?