A/C Request Circuit Diagnosis

CIRCUIT DESCRIPTION
The TCM uses the A/C Request signal in order to modify the shift program when the A/C is on. When the HVAC controls are in any position that enables the A/C compressor, the A/C Request circuit connects to B+. The TCM interprets this as a signal that the A/C compressor load is present.

DIAGNOSTIC AIDS
An intermittent may be caused by the following conditions:
^ Corrosion
^ Mis-routed harness
^ Rubbed through wire insulation
^ Broken wire inside the insulation
^ Refer to Diagnosis by Symptoms for Intermittents. Symptom Related Diagnostic Procedures





TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
2. The scan tool should indicate Yes with the HVAC controls in any position that requests the A/C compressor.
5. The ECM and TCM A/C Request circuits connect within the HVAC control head. An open circuit will only affect that individual A/C Request circuit. A short to ground or B+ will affect both circuits.