Radiator And A/C Condenser Fan Low Speed Circuit Troubleshooting
HVAC
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.
* If A/C refrigerant pressure is abnormal, the radiator fans are controlled based on engine coolant temperature.
* Before doing symptom troubleshooting, check for PGM-FI DTCs Initial Inspection and Diagnostic Overview.
1. Fuse check:
Fuse check
-1. Check the following fuse.
Is the fuse OK?
-YES- Go to step 2.
-NO- Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. A2-11 (20 A) fuse circuit.
2. Radiator fan relay check:
Radiator fan relay check
-1. Remove the radiator fan relay from the under-hood fuse/relay box, and test it Testing and Inspection.
Is the relay OK?
-YES- Go to step 3.
-NO- Replace the radiator fan relay.
3. A/C signal output check:
A/C signal output check
-1. Connect the HDS to the DLC.
-2. Turn the ignition switch to ON (II).
-3. Turn on the A/C.
-4. Check the FAN LOW CTRL in the PGM-FI Data List with the HDS.
Is the FAN LOW CTRL on?
-YES- Go to step 4.
-NO- Replace the PCM Service and Repair.
4. Open wire check (+B_MAIN_FAN line):
Open wire check (+B_MAIN_FAN line)
-1. Turn the ignition switch to LOCK (0).
-2. Measure the voltage between test points 1 and 2.
Is there battery voltage?
-YES- The +B_MAIN_FAN wire is OK. Go to step 5.
-NO- An open in the +B_MAIN_FAN wire. Replace the under-hood fuse/relay box.
5. Determination of possible failure area (radiator fan relay switch side circuit, radiator fan relay coil side circuit check):
Determination of possible failure area (radiator fan relay switch side circuit, radiator fan relay coil side circuit check)
-1. Connect terminals 1 and 2 with a jumper wire.
Do the A/C condenser and radiator fans run on low?
-YES- Go to step 6.
-NO- Go to step 8.
6. Radiator fan relay coil side power circuit check:
Radiator fan relay coil side power circuit check
-1. Disconnect the jumper wire.
-2. Turn the ignition switch to ON (II).
-3. Measure the voltage between test points 1 and 2.
Is there battery voltage?
-YES- Go to step 7.
-NO- Go to step 14.
7. Open wire check (RFC_RLY_COM line):
Open wire check (RFC_RLY_COM line)
-1. Turn the ignition switch to LOCK (0).
-2. Jump the SCS line with the HDS.
NOTE: This step must be done to protect the PCM from damage.
-3. Disconnect the following connector.
-4. Connect terminals 1 and 2 with a jumper wire.
-5. Turn the ignition switch to ON (II).
Do the A/C condenser and radiator fans run on low?
-YES- Replace the PCM Service and Repair.
-NO- Repair an open in the wire between the radiator fan relay and the PCM.
8. Open wire check (MAIN_FAN_MOTOR line):
Open wire check (MAIN_FAN_MOTOR line)
-1. Disconnect the jumper wire.
-2. Reinstall the radiator fan relay.
-3. Disconnect the following connector.
-4. Turn the ignition switch to ON (II), then turn on the A/C.
-5. Measure the voltage between test points 1 and 2.
Is there battery voltage?
-YES- The MAIN_FAN_MOTOR wire is OK. Go to step 9.
-NO- Repair an open in the wire between the radiator fan relay and the radiator fan motor.
9. Radiator fan motor test:
Radiator fan motor test
-1. Set the A/C button and fan control switch OFF, then turn the ignition switch to LOCK (0).
-2. Test the radiator fan motor Testing and Inspection.
Is the radiator fan motor OK?
-YES- Go to step 10.
-NO- Replace the radiator fan motor Service and Repair.
10. Fan control relay check:
Fan control relay check
-1. Remove the fan control relay from the under-hood fuse/relay box, and test it Testing and Inspection.
Is the relay OK?
-YES- Go to step 11.
-NO- Replace the fan control relay.
11. Open wire check (FAN_HI/LO_RLY_COM line):
Open wire check (FAN_HI/LO_RLY_COM line)
-1. Reconnect the radiator fan motor 2P connector.
-2. Turn the ignition switch to ON (II), then turn on the A/C.
-3. Measure the voltage between test points 1 and 2.
Is there battery voltage?
-YES- The FAN_HI/LO_RLY_COM wire is OK. Go to step 12.
-NO- Repair an open in the wire between the radiator fan motor and the fan control relay.
12. Open wire check (SUB_FAN_MOTOR line):
Open wire check (SUB_FAN_MOTOR line)
-1. Set the A/C button and fan control switch OFF, then turn the ignition switch to LOCK (0).
-2. Disconnect the following connector.
-3. Check for continuity between test points 1 and 2.
Is there continuity?
-YES- The SUB_FAN_MOTOR wire is OK. Go to step 13.
-NO- Check for an open in the wire between the fan control relay and the A/C condenser fan motor.
13. Open wire check (GND line):
Open wire check (GND line)
-1. Check for continuity between test points 1 and 2.
Is there continuity?
-YES- The GND wire is OK. Replace the A/C condenser fan motor Service and Repair.
-NO- Check for an open in the wire between the A/C condenser fan motor and body ground. If the wire is OK, check for poor ground at G301.
14. A/C diode B check:
A/C diode B check
-1. Turn the ignition switch to LOCK (0).
-2. Remove A/C diode B from the under-hood fuse/relay box.
-3. Using the diode setting (enu_255706_1.0) on a DVOM, check for current flow in both directions between A/C diode B terminals No. 1 and No. 2.
Is there current flow in only one direction?
-YES- Go to step 15.
-NO- Replace the A/C diode B.
15. Open wire check (IG2_A/C line):
Open wire check (IG2_A/C line)
-1. Turn the ignition switch to ON (II).
-2. Measure the voltage between test points 1 and 2.
Is there battery voltage?
-YES- The IG2_A/C wire is OK. Replace the under-hood fuse/relay box.
-NO- Repair an open in the wire between the No. B22 (7.5 A) fuse in the under-dash fuse/relay box and A/C diode B.