A/C Signal Circuit Troubleshooting
  1. Measure the evaporator temperature sensor resistance between climate control unit connector A (28P) No. 23 terminal and connector B (12P) No. 10 terminal.
Is the resistance less than 24 kΩ?
YES -
Check for loose wires or poor connections at climate control unit connectors. If the connections are good, substitute a known-good climate control unit and recheck. If the symptom goes away, replace the original climate control unit .■
NO -
Test the evaporator temperature sensor. ■
  1. Disconnect the A/C compressor 3P connector.