Cooling Fan Controls Symptom Troubleshooting (K20Z)

Cooling Fan Controls Symptom Troubleshooting

Symptom Diagnostic Procedure Also check for
Engine overheats 1.
2.
3.

4.

5.
6.

7.
8.

9.
10.
11.
12. Inspect the water pump.
Check the thermostat.
Check for any engine coolant leakage (from gaskets, hoses, O-rings, etc.).
Check for dirt, leaves, or insects on radiator and condenser.
Check for a damaged or deformed fan shroud.
Check for a plugged or deteriorated radiator hoses.
Check the radiator cap.
Inspect the fan motors or fan relays.
Check for plugged heater core or hoses.
Check the coolant level.
Check for deteriorated coolant.
Check for a damaged cylinder head gasket.
The A/C condenser fan runs at low speed, but it does not run at high speed when the engine coolant temperature is above 93 °C (199 °F) A/C condenser fan high speed circuit troubleshooting. Cleanliness and tightness of all connectors
With the A/C off and the engine coolant temperature at 93 °C ( 199 °F) or below, the radiator fan runs at high speed and the A/C condenser fan does not run. When the engine coolant temperature is above 93 °C ( 199 °F), both fans run at high speed Remove the fan control relay, and test.
If the relay is faulty, replace it.
If the relay is OK, check for a short in the wire between the fan control relay 5P socket terminal
No. 1 and radiator fan motor 2P connector terminal No. 1.
Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan run at high speed with the ignition switch ON (II), the A/C off, and the engine coolant temperature below 90 °C (194 °F) Check for a short in the wire between A/C condenser fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A5. Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan run at low speed with the ignition switch ON (II) and the A/C off Check for a short in the wire between radiator fan relay 4P socket terminal No. 4 and ECM/PCM connector terminal A4. Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan do not run at low speed with the A/C on Radiator and A/C condenser fans low speed circuit troubleshooting. Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan run at low speed, but radiator fan does not run at high speed when the engine coolant temperature is above
93 °C (199 °F) Radiator fan high speed circuit troubleshooting. Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan do not run at high speed when the engine coolant temperature is above 93 °C (199 °F) Check for an open in the wire between A/C condenser fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A5. Cleanliness and tightness of all connectors

Symptom	Diagnostic Procedure		Also check for
Engine overheats	1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.	Inspect the water pump. Check the thermostat. Check for any engine coolant leakage (from gaskets, hoses, O-rings, etc.). Check for dirt, leaves, or insects on radiator and condenser. Check for a damaged or deformed fan shroud. Check for a plugged or deteriorated radiator hoses. Check the radiator cap. Inspect the fan motors or fan relays. Check for plugged heater core or hoses. Check the coolant level. Check for deteriorated coolant. Check for a damaged cylinder head gasket.
The A/C condenser fan runs at low speed, but it does not run at high speed when the engine coolant temperature is above 93 °C (199 °F)	A/C condenser fan high speed circuit troubleshooting.		Cleanliness and tightness of all connectors
With the A/C off and the engine coolant temperature at 93 °C ( 199 °F) or below, the radiator fan runs at high speed and the A/C condenser fan does not run. When the engine coolant temperature is above 93 °C ( 199 °F), both fans run at high speed	Remove the fan control relay, and test. If the relay is faulty, replace it. If the relay is OK, check for a short in the wire between the fan control relay 5P socket terminal No. 1 and radiator fan motor 2P connector terminal No. 1.		Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan run at high speed with the ignition switch ON (II), the A/C off, and the engine coolant temperature below 90 °C (194 °F)	Check for a short in the wire between A/C condenser fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A5.		Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan run at low speed with the ignition switch ON (II) and the A/C off	Check for a short in the wire between radiator fan relay 4P socket terminal No. 4 and ECM/PCM connector terminal A4.		Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan do not run at low speed with the A/C on	Radiator and A/C condenser fans low speed circuit troubleshooting.		Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan run at low speed, but radiator fan does not run at high speed when the engine coolant temperature is above 93 °C (199 °F)	Radiator fan high speed circuit troubleshooting.		Cleanliness and tightness of all connectors
Both the radiator fan and the A/C condenser fan do not run at high speed when the engine coolant temperature is above 93 °C (199 °F)	Check for an open in the wire between A/C condenser fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A5.		Cleanliness and tightness of all connectors