A/C Signal Circuit Troubleshooting (Climate Control System)
A/C Signal Circuit Troubleshooting
NOTE:
- If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Run the self-diagnostic function, and check the DTC B1241. Before performing any other troubleshooting, repair the cause of the inoperative blower motor.
- Do not use this troubleshooting procedure if any of the following items are operative: The A/C condenser fan, the radiator fan, or the A/C compressor, or if the heater is inoperative. Refer to the symptom troubleshooting index.
- Before doing symptom troubleshooting, check for PGM-FI DTCs Initial Inspection and Diagnostic Overview.
1. Turn the ignition switch to ON (II).
2. Check if the blower motor operates at all speeds.
Does the blower motor operate at all speeds?
YES -
Go to step 3.
NO -
Repair the problem in the blower motor circuit.�
3. Do the sensor input display mode.
Is Sensor �V�5 (evaporative outlet air temperature) above 3 °C?
YES -
Go to step 4.
NO -
Go to step 15.
4. Turn the ignition switch to LOCK (0).
5. Disconnect climate control unit connector A (28P).
6. Turn the ignition switch to ON (II).
7. Measure the voltage between climate control unit connector A (28P) terminal No. 21 and body ground.
Is there battery voltage?
YES -
Replace the climate control unit Climate Control Unit Removal/Installation.�
NO -
Go to step 8.
8. Turn the ignition switch to LOCK (0).
9. Disconnect the A/C compressor clutch 3P connector.
10. Turn the ignition switch to ON (II).
11. Measure the voltage between A/C compressor clutch 3P connector terminal No. 2 and body ground.
Is there battery voltage?
YES -
Go to step 12.
NO -
Go to step 14.
12. Turn the ignition switch to LOCK (0).
13. Check for continuity between A/C compressor clutch 3P connector terminals No. 1 and No. 2.
Is there continuity?
YES -
Repair an open in the wire between the A/C compressor and the climate control unit.�
NO -
Replace the thermal protector Service and Repair.�
14. Measure the voltage between under-dash fuse/relay box connector F (33P) terminal No. 5 and body ground.
Is there battery voltage?
YES -
Repair an open in the wire between the A/C compressor and the driver's under-dash fuse/relay box.�
NO -
Check for loose wire or poor connections at driver's under-dash fuse/relay box connector F (33P) terminal No. 5. If the connections are good, substitute a known-good driver's under-dash fuse/relay box, and recheck. If the symptom goes away, replace the original driver's under-dash fuse/relay box; USA models Drivers Under-Dash Fuse/Relay Box (Drivers MICU) Removal and Installation (USA models), Canada models Drivers Under-Dash Fuse/Relay Box (Drivers MICU) Removal and Installation (USA models).�
15. Turn the ignition switch to LOCK (0).
16. Disconnect climate control unit connectors A (28P) and B (12P).
17. Measure the evaporator temperature sensor resistance between climate control unit connector A (28P) terminal No. 23 and connector B (12P) terminal No. 10.
Is the resistance less than 24 kOhms?
YES -
Check for loose wires or poor connections at the 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 Climate Control Unit Removal/Installation.�
NO -
Go to step 18.�
18. Check for continuity between climate control unit connector A (28P) terminal No. 23 and evaporator temperature sensor 2P connector terminal No. 2.
Is there continuity?
YES -
Go to step 19.
NO -
Repair an open in the wire between the climate control unit and the evaporator temperature sensor.�
19. Check for continuity between climate control unit connector B (12P) terminal No. 10 and evaporator temperature sensor 2P connector terminal No. 1.
Is there continuity?
YES -
Test the evaporator temperature sensor Evaporator Temperature Sensor Test.�
NO -
Repair an open in the wire between the climate control unit and the evaporator temperature sensor.�