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. Heating/Air Conditioning
- Before performing symptom troubleshooting, check for powertrain 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 to 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 No. 1 terminal 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 No. 1 and No. 2 terminals with a jumper wire.
Do the A/C condenser and radiator fans run on low?
YES - Go to step 9.
NO - Go to step 19.
9. Turn the ignition switch to LOCK (0).
10. Disconnect the jumper wire.
11. Turn the ignition switch to ON (II).
12. Measure the voltage between the radiator fan relay 4P socket No. 3 terminal and body ground.
Is there battery voltage?
YES - Go to step 13.
NO - Go to step 38.
13. Turn the ignition switch to LOCK (0).
14. Reinstall the radiator fan relay.
15. Jump the SCS line with the HDS.
NOTE: This step must be done to protect the engine control module (ECM)/powertrain control module (PCM) from damage.
16. Disconnect ECM/PCM connector A (44P).
17. Connect the ECM/PCM connector A (44P) No. 4 terminal to body ground with a jumper wire.
18. Turn the ignition switch to 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) No. 4 terminal. 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.
19. Turn the ignition switch to LOCK (0).
20. Disconnect the jumper wire.
21. Reinstall the radiator fan relay.
22. Disconnect the radiator fan 2P connector.
23. Turn the ignition switch to ON (II), then set the A/C button and fan control dial ON.
24. Measure the voltage between the radiator fan 2P connector No. 2 terminal and body ground.
Is there battery voltage?
YES - Go to step 25.
NO - Repair open in the wire between the radiator fan relay and the radiator fan.
25. Set the A/C button and fan control dial OFF, then turn the ignition switch to LOCK (0).
26. Reconnect the radiator fan 2P connector.
27. Connect the radiator fan 2P connector No. 1 terminal to body ground with a jumper wire.
28. Turn the ignition switch to ON (II), then set the A/C button and fan control dial ON.
Does the radiator fan run?
YES - Go to step 29.
NO - Replace the radiator fan motor.
29. Set the A/C button and fan control dial OFF, then turn the ignition switch to LOCK (0).
30. Disconnect the jumper wire.
31. Remove the fan control relay from the under-hood relay box, and test it.
Is the relay OK?
YES - Go to step 32.
NO - Replace the fan control relay.
32. Turn the ignition switch to ON (II), then set the A/C button and fan control dial ON.
33. Measure the voltage between the fan control relay 5P socket No. 1 terminal and body ground.
Is there battery voltage?
YES - Go to step 34.
NO - Repair open in the wire between the radiator fan and the fan control relay.
34. Set the A/C button and fan control dial OFF, then turn the ignition switch to LOCK (0).
35. Disconnect the A/C condenser fan 2P connector.
36. Check for continuity between the fan control relay 5P socket No. 4 terminal and the A/C condenser fan 2P connector No. 2 terminal.
Is there continuity?
YES - Go to Step 37.
NO - Repair open in the wire between the fan control relay and A/C condenser fan.
37. Check for continuity between the A/C condenser fan 2P connector No. 1 terminal 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.
38. Turn the ignition switch to LOCK (0).
39. Remove A/C diode A from the under-hood fuse/relay box.
40. Using the diode setting on a DVOM, check for current flow in both directions between the A/C diode A No. 1 and No. 2 terminals.
Is there current flow in only one direction?
YES - Go to step 41.
NO - Replace A/C diode A.
41. Turn the ignition switch to ON (II).
42. Measure the voltage between the A/C diode A 2P socket No. 2 terminal 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 (10 A) fuse in the under-dash fuse/relay box and A/C diode A.