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 and A/C condenser fans are controlled based only on engine coolant temperature.
Before doing symptom troubleshooting, check for PGM-FI DTCs.
1.
Fuse check:

Fuse check
?1.
Check the following fuse.
Fuse
No. A12-9 (MAIN FAN MTR) (30 A)
Location
Under-hood fuse/relay box

Is the fuse OK?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Replace the fuse, and recheck. If the fuse blows again, repair a short in the No. A12-9 (MAIN FAN MTR) (30 A) fuse circuit.?
2.
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). Make sure the A/C system is OFF, then start the engine.

?3.
Turn the blower control dial ON, then momentarily turn ON the A/C with the A/C button.
NOTE: Do not run the A/C for more than a few seconds with the engine running or damage to the A/C system will result.

?4.
Check the parameter(s) below with the HDS.
Signal
Threshold
Current conditions
Values
Unit
Values
Unit
FAN LOW CTRL
ON
      

Is the FAN LOW CTRL on with the A/C on?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Update the PCM if it does not have the latest software, or substitute a known-good PCM, and recheck.?
3.
Radiator fan and fan control relays check:

Radiator fan and fan control relays check
?1.
Turn the ignition switch to LOCK (0).

?2.
Remove the relay circuit board from the under-hood fuse/relay box, and test it.

Are the relays OK?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
4.
Open wire check (+B MAIN FAN line):

Open wire check (+B MAIN FAN line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
IG LOCK (0)
Relay circuit board connector B (14P): disconnected
Test circuit
+B MAIN FAN
Test point 1
Relay circuit board connector B (14P) No. 7 (GRN)
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B MAIN FAN wire is OK. Go to step 5.
     
NO
     
     
     
Repair an open in the wire between the No. A12-9 (MAIN FAN MTR) (30 A) fuse and the relay circuit board in the under-hood fuse/relay box.?
5.
Determine possible failure area (radiator fan relay switch side circuit, radiator fan relay coil side circuit):

Determine possible failure area (radiator fan relay switch side circuit, radiator fan relay coil side circuit)
?1.
Connect terminals A and B with a jumper wire.
Terminal A
Relay circuit board connector B (14P) No. 1 (BLU)
Terminal B
Relay circuit board connector B (14P) No. 7 (GRN)


Do the A/C condenser and radiator fans run on low?

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
Go to step 7.
6.
Open wire check (FAN LO SIGNAL line):

Open wire check (FAN LO SIGNAL line)
?1.
Disconnect the jumper wire.

?2.
Reinstall the relay circuit board into the under-hood fuse/relay box.

?3.
Jump the SCS line with the HDS.

NOTE: This step must be done to protect the PCM from damage.

?4.
Disconnect the following connector.

?5.
Connect terminals A and B with a jumper wire.
Terminal A
PCM connector A (51P) No. 9 (WHT)
Terminal B
Body ground


?6.
Turn the ignition switch to ON (II).

Do the A/C condenser and radiator fans run on low?

     
YES
     
     
     
Update the PCM if it does not have the latest software, or substitute a known-good PCM, and recheck.?
     
NO
     
     
     
Repair an open in the wire between the relay circuit board in the under-hood fuse/relay box and the PCM, or between the No. B1 (7.5 A) fuse in the under-dash fuse/relay box and the relay circuit board in the under-hood fuse/relay box.?
7.
Open wire check (MAIN FAN MOTOR line):

Open wire check (MAIN FAN MOTOR line):
?1.
Disconnect the following connector.

?2.
Measure the voltage between test points 1 and 2.
Test condition
IG LOCK (0)
 
Radiator fan motor 2P connector: disconnected
 
Relay circuit board connector B (14P): disconnected
 
Relay circuit board connector B (14P) No. 1 and No. 7: jumped
Test circuit
MAIN FAN MOTOR
Test point 1
Radiator fan motor 2P connector No. 1 (BLU)
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The MAIN FAN MOTOR wire is OK. Go to step 8.
     
NO
     
     
     
Repair an open in the wire between the relay circuit board in the under-hood fuse/relay box and the radiator fan motor.?
8.
Radiator and A/C condenser fan motors test:

Radiator and A/C condenser fan motors test
?1.
Test the radiator and the A/C condenser fan motors.

Are the radiator and A/C condenser fan motors OK?

     
YES
     
     
     
Go to step 9.
     
NO
     
     
     
9.
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.
Measure the voltage between test points 1 and 2.
Test condition
IG LOCK (0)
 
Relay circuit board connector B (14P): disconnected
 
Relay circuit board connector B (14P) No. 1 and No. 7: jumped
Test circuit
FAN HI/LO RLY COM
Test point 1
Relay circuit board connector B (14P) No. 14 (PNK)
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The FAN HI/LO RLY COM wire is OK. Go to step 10.
     
NO
     
     
     
Repair an open in the wire between the radiator fan motor and the relay circuit board in the under-hood fuse/relay box.?
10.
Open wire check (SUB FAN MOTOR line):

Open wire check (SUB FAN MOTOR line)
?1.
Disconnect the following connector.

?2.
Connect terminals A and B with a jumper wire.
Terminal A
Relay circuit board connector B (14P) No. 13 (LT GRN)
Terminal B
Relay circuit board connector B (14P) No. 14 (PNK)


?3.
Measure the voltage between test points 1 and 2.
Test condition
IG LOCK (0)
 
A/C condenser fan motor 2P connector: disconnected
 
Relay circuit board connector B (14P): disconnected
 
Relay circuit board connector B (14P) No. 1 and No. 7: jumped
 
Relay circuit board connector B (14P) No. 13 and No. 14: jumped
Test circuit
SUB FAN MOTOR
Test point 1
A/C condenser fan motor 2P connector No. 1 (LT GRN)
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
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.?
     
NO
     
     
     
Repair an open in the wire between the relay circuit board in the under-hood fuse/relay box and the A/C condenser fan motor.?