Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting
Radiator and A/C Condenser Fan Low Speed Circuit TroubleshootingNOTE:
- Do not use this troubleshooting procedure if the A/C compressor is inoperative. Refer to the symptom troubleshooting index. Symptom Related Diagnostic Procedures
- Before performing symptom troubleshooting, check for power-train DTCs.
1. Check the No. 7 (20 A: M/T) or (30 A: A/T) fuse in the under-hood fuse/relay box, and the No. 36 (10 A) fuse in the under-dash fuse/relay box.
Are the fuses OK?
YES - Go to step 2.
NO - Replace the fuses, and recheck. If the fuses blow again, check for a short in the No. 7 (20 A: M/T) or (30 A: A/T) and No. 36 (10 A) fuses circuit.
2. Remove the radiator fan relay from the under-hood fuse/relay box, and test it.
Is the relay OK ?
YES - Go to step 3.
NO - Replace the radiator fan relay.
3. Connect the HDS to the DLC.
4. Turn the ignition switch ON (II).
5. Turn on the A/C on the HVAC control unit.
6. Check the FAN LOW CTRL in the PGM-FI Data List with the HDS.
Is the FAN LOW CTRL on?
YES - Go to step 7.
NO - Substitute a known-good ECM/PCM, and retest. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
7. Measure the voltage between the radiator fan relay 4P socket terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 8.
NO - Replace the under-hood fuse/relay box.
8. Connect the radiator fan relay 4P socket terminals No. 1 and No. 2 with a jumper wire.
Do the A/C condenser and radiator fans run on low?
YES - Go to step 9.
NO - Go to step 17.
9. Disconnect the jumper wire.
10. Turn the ignition switch ON (II).
11. Measure the voltage between the radiator fan relay 4P socket terminal No. 3 and body ground.
Is there battery voltage?
YES - Go to step 12.
NO - Go to step 35.
12. Turn the ignition switch OFF.
13. Reinstall the radiator fan relay.
14. Disconnect ECM/PCM connector A (44P).
15. Connect the ECM/PCM connector A (44P) terminal No. 4 to body ground with a jumper wire.
16. Turn the ignition switch ON (II).
Do the A/C condenser and radiator fans run on low?
YES - Check for loose wires or poor connections at ECM/PCM connector A (44P) terminal No. 4. If the connections are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original ECM/PCM.
NO - Repair open in the wire between the radiator fan relay and the ECM/PCM.
17. Disconnect the jumper wire.
18. Reinstall the radiator fan relay.
19. Disconnect the radiator fan 2P connector.
20. Turn the ignition switch ON (II), then set the A/C button and fan control dial ON.
21. Measure the voltage between the radiator fan 2P connector terminal No. 2 and body ground.
Is there battery voltage?
YES - Go to step 22.
NO - Repair open in the wire between the radiator fan relay and the radiator fan.
22. Set the A/C button and fan control dial OFF, then turn the ignition switch OFF.
23. Reconnect the radiator fan 2P connector.
24. Connect the radiator fan 2P connector terminal No. 1 to body ground with a jumper wire.
25. Turn the ignition switch ON (II), then set the A/C button and fan control dial ON.
Does the radiator fan run?
YES - Go to step 26.
NO - Replace the radiator fan motor.
26. Set the A/C button and fan control dial OFF, then turn the ignition switch OFF.
27. Disconnect the jumper wire.
28. Remove the fan control relay from the under-hood relay box, and test it.
Is the relay OK?
YES - Go to step 29.
NO - Replace the fan control relay.
29. Turn the ignition switch ON (II), then set the A/C button and fan control dial ON.
30. Measure the voltage between the fan control relay 5P socket terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 31.
NO - Repair open in the wire between the radiator fan and the fan control relay.
31. Set the A/C button and fan control dial OFF, then turn the ignition switch OFF.
32. Disconnect the A/C condenser fan 2P connector.
33. Check for continuity between the fan control relay 5P socket terminal No. 4 and the A/C condenser fan 2P connector terminal No. 2.
Is there continuity?
YES - Go to step 34.
NO - Repair open in the wire between the fan control relay and the A/C condenser fan.
34. Check for continuity between the A/C condenser fan 2P connector terminal No. 1 and body ground.
Is there continuity?
YES - Replace the A/C condenser fan motor.
NO - Check for an open in the wire between the A/C condenser fan and body ground. If the wire is OK, check for poor ground at G301.
35. Turn the ignition switch OFF.
36. Remove A/C diode A from the under-hood fuse/relay box.
37. Using the diode setting (-K-) on a DVOM, check for current flow in both directions between the A/C diode A terminals No. 1 and No. 2.
Is there current flow in only one direction?
YES - Go to step 38.
NO - Replace A/C diode A.
38. Turn the ignition switch ON (II).
39. Measure the voltage between the A/C diode A 2P socket terminal No. 2 and body ground.
Is there battery voltage?
YES - Replace the under-hood fuse/relay box.
NO - Repair open in the wire between the No. 36 fuse in the under-dash fuse/relay box and A/C diode A.