Operation CHARM: Car repair manuals for everyone.

Component Tests and General Diagnostics

If the heater outlet air temperature cannot be adjusted with the temperature control knob on the heater-A/C control panel, the following could require service:

- The heater-A/C control.
- The temperature control cable (not connected, not routed, or not adjusted properly).
- The blend-air door.
- Improper engine coolant temperature.