1986-1989 Corvette C68 Electronic Climate Control AC Services


The AC Controller Module

The controller is the computer and the power supply for the air conditioning system. It measures interior and exterior temperatures and the sun load falling on the car, and attempts to match interior temperature to the user set point. It commands the programmer module, the blend door motor, and the blower control modules.


Common Problems with the Controller

  • The C68 ECC Electronic Climate Control AC HVAC controller buttons, bulbs, power supply, capacitors, internal connectors and the display commonly fail

  • The faceplate detaches from the circuit board and buttons stop working

  • The display and LEDs flash like crazy and display gibberish info

  • The compressor clutch request can fail, resulting in no compressor or AC



The 86-89 AC Programmer Module

The HVAC programmer module houses vacuum control solenoids and the blend door motor controller.


Common Problems with the Programmer

  • Heat and vibration can cause the solder joints to break down

  • Power Supply capacitors frequently fail

  • The blend door drive circuitry frequently fails, causing the unit to blow hot when cold is selected, or cold air to blow when hot air is selected

  • Solenoids can stick on or off, causing air to be diverted to the wrong location or not pass through the evaporator or heater core. For an additional fee (optional), we can test the vacuum portion of the cluster. If needed, we can repair it as well



The Blend Door Actuator Motor

The blend door motor moves the blend door inside the air handling box. This causes more or less air from the blower to flow through the heater core, causing the air coming from the air handling box to be warmer or cooler.


Common Problems with the Blend Door Actuator

  • Moisture and dust from the system can cause the motor to seize or the gearbox to fail

  • The position sensor becomes uncalibrated over time



The Blower Control Module

The Blower Control Module is the electronic speed controller for the blower motor. It also contains the electronic compressor clutch relay.


Common Problems with the Blower Control Module

  • The Blower Control Module transistor fails frequently. It typically fails shorted, causing the fan motor to run when it shouldn't.

  • The Blower Control Module contains the transistorized relay which turns the compressor clutch off and on. If your compressor clutch won't energize, check this!

  • We can test this component, but it is sealed and not repairable.



It can sometimes be difficult to know which component(s) have failed, so we're here to help. If you don't know what the problem is with your AC, you can always contact us and ask which components to ship. Feel free to ship all four components. We'll test everything together at no charge!



All Services Include

  • Free inspection of the climate control electronics

  • Complete cleaning inside the controller, programmer or blend door actuator

  • Bench test of all C68 HVAC components and all electrical functions of the controller, programmer, blower control module and blend door motor

  • This is not an exchange service. Your components will be returned to you!

  • 1 year warranty on parts and labor





  • Repair 86-89 HVAC Controller: $275.00

  • Repair 86-89 HVAC Programmer Electronics: $125.00

  • Optional Vacuum Test Programmer: $60.00

  • Programmer Vacuum Repair available if needed

  • 86-89 Blend Door Actuator w/new motor and gearbox and calibration: $349.95



These repairs are the most common needed for the 86-89 Electronic Climate Control, and do not include replacement of missing components, or the replacement of display or logic board. When your components arrive, we will diagnose each at no charge, then contact you with photos of the problem and an exact repair total, and wait for your approval before making any repairs.



Before You Ship

Before you send the climate control components, check the following:

  • Check the GAGES and CTSY/CLK fuses.

  • If you're having problems with the blower motor not turning, check the A/C Underhood Fuse

  • Turn on the ignition, and watch the "Ext Temp" light. If it flashes, count the number of flashes and report that info to us. Also look at the display and tell us what number is displayed.

  • The programmer module is located in the drivers side footwell, just above the gas pedal. Follow the colored vacuum lines to it. There is a metal keeper which holds on the block of vacuum lines. Use needle nose pliers to remove it, or just cut it with diagonal cutters then remove all vac lines as an assembly. We ship the programmer back with a lock nut and washer that will let you reattach the vacuum lines.