Customer Concern: There is no temperature change when turning the temperature control knob. Manual climate control system.
Tests/Procedures: 1. Locate the blend door actuator, on the passenger side of the heater case, to the driver side of the glove box opening. Watch the square shaft on the top of the actuator and see if it is moving when turning the temperature control knob.
2. If the blend door actuator shaft moves, but there is no temperature change, the blend door is broken.
3. If the blend door actuator shaft does not move, make sure that the Purple/Orange wire to the blend door actuator has battery voltage (from the RUN fuse in the inside fuse box) and the Black wire is ground.
4. If OK, back probe the Red/White wire at the temperature control knob, with the blend door actuator connected, and check for greater than 9 volts reference voltage out of the blend door actuator to the temperature control knob.
Then check the Red/Light Green wire for ground from the actuator, and if both are OK, monitor the Yellow/Light Green temperature control lever output wire to see if voltage goes up and down (from about 9 volts cold to about 2 volts hot) when moving the temperature lever back and forth.
5. If all is OK, and the blend door actuator doesn't move, replace the blend door actuator.
7. If the Red/White wire has normal voltage, and the Red/Light Green wire is a good ground, but the Yellow/Light Green wire doesn't change properly, the potentiometer in the temperature control head has failed.
Potential Causes: Defective Control Knob Potentiometer
Broken Temperature Blend Door
Defective Temperature Blend Door Actuator
Tech Tips: If replacing the blend door actuator, make sure the replacement part has a sticker with the letters "MAN" on it. If it says "ATC" or "EATC" on it, it is for an automatic temperature control system, and will NOT work on this application.
