Diesel Data: Automotive Repair

Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting

Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting

NOTE:
- Do not use this troubleshooting procedure if the A/C compressor is inoperative. Refer to the symptom troubleshooting index.
- Before performing symptom troubleshooting, check for powertrain DTCs.

1. Check the No. 19 (20 A) fuse in the under-hood fuse/relay box, and the No. 16 (7.5 A) fuse in the under-dash fuse/relay box.

Are the fuses OK?

YES - Go to step 2.

NO - Replace the fuse(s), and recheck.

2. Remove the A/C condenser fan relay from the under-hood fuse/relay box, and test it.

Is the relay OK?

YES - Go to step 3.

NO - Replace the A/C condenser fan relay.




3. Measure the voltage between the No. 1 terminal of the A/C condenser fan relay 4P socket and body ground.

Is there battery voltage?

YES - Go to step 4.

NO - Replace the under-hood fuse/relay box.




4. Connect the No. 1 and No. 2 terminals of the A/C condenser fan relay 4P socket with a jumper wire.

Does the A/C condenser fan run?

YES - Go to step 5.

NO - Go to step 13.

5. Disconnect the jumper wire.
6. Turn the ignition switch ON (II).




7. Measure the voltage between the No. 4 terminal of the A/C condenser fan relay 4P socket and body ground.

Is there battery voltage?

YES - Go to step 8.

NO - Repair open in the wire between the No. 16 fuse in the under-dash fuse/relay box and the A/C condenser fan relay.

8. Reinstall the A/C condenser fan relay.
9. Remove the A/C diode from the left side of dash.




10. On the A/C diode, check for current flow in both directions between the No. 1 and No. 2 terminals. and between the No. 2 and No. 3 terminals.

Does current flow match the diagram?

YES - Go to step 11.

NO - Replace the A/C diode.

11. Turn the ignition switch ON (II).




12. Measure the voltage between the No. 2 terminal of the A/C diode 3P connector and body ground.

Is there battery voltage?

YES - Repair open in the wire between the A/C diode and the A/C pressure switch.

NO - Repair open in the wire between the A/C condenser fan relay and the A/C diode.

13. Disconnect the jumper wire.
14. Reinstall the A/C condenser fan relay.
15. Disconnect the A/C condenser fan 2P connector.
16. Turn the ignition switch ON (II), then turn the A/C and fan switches ON.




17. Measure the voltage between the No. 2 terminal of the A/C condenser fan 2P connector and body ground.

Is there battery voltage?

YES - Go to step 18.

NO - Repair open in the wire between the A/C condenser fan relay and the A/C condenser fan.

18. Turn the A/C and fan switches OFF, then turn the ignition switch OFF.
19. Reconnect the A/C condenser fan 2P connector.




20. Connect the No.1 terminal of the A/C condenser fan 2P connector to body ground with a jumper wire.

21. Turn the ignition switch ON (II), then turn the A/C and fan switches ON.

Does the A/C condenser fan run?

YES - Go to step 22.

NO - Replace the A/C condenser fan motor.

22. Turn the A/C and fan switches OFF, then turn the ignition switch OFF.
23. Disconnect the jumper wire.
24. Remove the fan control relay from the multi-relay box, and test it.

Is the relay OK?

YES - Go to step 25.

NO - Replace the fan control relay.

25. Turn the ignition switch ON (II), then turn the A/C and fan switches ON.




26. Measure the voltage between the No. 1 terminal of the fan control relay 5P socket and body ground.

Is there battery voltage?

YES - Go to step 27.

NO - Repair open in the wire between the A/C condenser fan and the fan control relay.

27. Turn the A/C and fan switches OFF, then turn the ignition switch OFF.
28. Disconnect the radiator fan 2P connector.




29. Check for continuity between the No. 4 terminal of the fan control relay 5P socket and the No. 2 terminal of the radiator fan 2P connector.

Is there continuity?

YES - Go to step 30.

NO - Repair open in the wire between the fan control relay and the radiator fan.




30. Check for continuity between the No. 1 terminal of the radiator fan 2P connector and body ground.

Is there continuity?

YES - Replace the radiator fan motor.

NO - Check for an open in the wire between the radiator fan and body ground. If the wire is OK, check for poor ground at G301.