Temperature Controls Diagnosis - Tempmatic Climate Control System

Perform this diagnosis if warm air only, cold air only, or poor temperature regulation exist.
1. Remove glove box assembly to provide access to programmer and temperature door threaded rod. Use inspection mirror to view temperature door operation.
2. With engine running at normal operating temperature, set panel selector at "NORM," and blower switch at "HI."
3. Move temperature selector from "65" to "85" and then return to "65." Observe temperature door threaded rod and programmer crank operation while moving temperature selector. Air outlet temperature should increase and decrease with corresponding changes in lever position.
4. If there is no change in temperature during step 3 and programmer crank fails to move, check control cable for free movement. Check cable connections at control panel and programmer. Correct any faults.
5. If there is no change in temperature during step 3, and programmer lever/control cable moves correctly, perform the following:
a. Check to see if vacuum motor linkage is disconnected at programmer.
b. Release temperature door threaded rod from plastic retainer at programmer. Move temperature door through full travel with rod, checking to see that there are no obstructions. If movement is restricted, remove heater case and core. Correct as needed.
6. If temperature door moves freely in step 5, and only cold air flows in step 3, check for vacuum at water control valve. If vacuum is present, holding valve closed, check A/C control for source of vacuum. Vacuum should only be present when control is in "MAX A/C" position. If valve fails to close with vacuum applied, or fails to open when vacuum is not applied, it must be replaced. If no vacuum is present in "MAX A/C" position, check vacuum circuit for disconnected lines, blockages, etc.
7. If temperature door moves freely, heater water control valve is operating properly, and only cold air flows in step 3, check for vacuum at engine vacuum line connection of vacuum checking relay. If no vacuum is present, check vacuum circuit for leaks. If vacuum is present, apply vacuum directly to vacuum motor. If motor operates, check motor vacuum line for leaks, blockages, etc. If motor does not operate with direct application of vacuum, it is defective and must be replaced. If motor operates, and no defects are found in vacuum lines, replace vacuum checking relay.
8. If temperature door moves freely, and only warm air flows in step 3, observe operation of programmer link. At full heat position, link should be drawn fully into vacuum motor. Disconnect hose from vacuum motor. If link moves out from motor, replace compensator. If link does not move, replace vacuum motor.
9. If temperature varies in step 3, perform the following:
a. Check to ensure in-car air hose is properly connected. Check hose for leaks, kinks, etc. Correct as needed.
b. Check to ensure temperature door is properly adjusted. Check adjustment of temperature control cable and programmer control lever. Correct as needed.
c. If problem persists after performing steps a and b, replace compensator assembly in programmer.