radiator fan
10-18-2012, 05:10 PM
#1
Advanced
Thread Starter
radiator fan
Will just one fan come on when your coolant comes of temperature? In other words if just one of my fans starts running is the other fans switch likely out?
10-18-2012, 05:46 PM
#3
Three Wheelin'
They're fed by different leads and have different grounding locations, but the schematic of the fan relay, shows that they should both operate at the same time.
Try turning the AC on and see if they both go to high speed.
Try turning the AC on and see if they both go to high speed.
10-20-2012, 03:03 PM
#7
Three Wheelin'
It is not the fan switch. They should both run at the same time. Are they running in high or low speed? If they both run at high speed, but only one runs at low speed you probably have a bad resistor.
Here is a check list to diagnose the problem.
The fans are controlled by the cooling fan relay which is in turn controlled by the thermo switch, and the a/c system. Whenever they are closed, both fans should run at the same speed at the same time. If only one is working or you only get high speed operation, there is a problem.
You should always have power available to the relay, so the fans can run at any time. Remove the cooling fan relay. It is the large rectangular silver relay in the back of the panel. Check the diagram on the fuse panel cover for the exact location. All of the following checks can be made at the fuse panel. You will need a bright light to see the markings on the fuse panel.
1. In the Bosch world, a terminal designation of “30” means it is un-switched battery voltage. Check for voltage at positions 30 M1 and 30 M2. You should get 12v + at both positions. If no voltage, check the wiring from the battery, the connections to the fuse panel, and the fuse panel itself. You will have to pull the fuse panel up, but disconnect the battery before messing around under the fuse panel.
2. Check for continuity between ground and the temp switch positions "TS" and "TF" on the fuse panel. If you have continuity, the thermo switch is calling for fan operation. If the car is cold, the thermo switch is bad.
3. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle.
4. Connect the jumper between M1 30 to M1, the drivers fan should run at high speed. If the fan does not run, check for voltage in the connector at the fan motor, if you have voltage but the fan does not run, replace the fan motor.
5. Check the passenger fan by connecting the jumper between M2 30 and M2, the passenger fan should run at high speed. If not, the same drill.
6. Next connect the jumper between M1 30 and V1, the drivers fan should run at low speed. If not the resistor or wiring is bad. Check for voltage at the radiator fan connector and then check the resistance across the resistor.
7. Next connect the jumper between M2 30 and V2, the passenger fan should run at low speed. If it does not run, check the wiring and resistor.
If the car is still running hot and the fans are working properly, you have other issues, like a clogged radiator, water pump failing, air bubbles, bad thermostat, or a bad head gasket.
The other positions on the fan relay are:
X = battery power to the logic board in the relay
31 = Ground for the logic board in the relay
AC = AC freeze protection switch
Here is a check list to diagnose the problem.
The fans are controlled by the cooling fan relay which is in turn controlled by the thermo switch, and the a/c system. Whenever they are closed, both fans should run at the same speed at the same time. If only one is working or you only get high speed operation, there is a problem.
You should always have power available to the relay, so the fans can run at any time. Remove the cooling fan relay. It is the large rectangular silver relay in the back of the panel. Check the diagram on the fuse panel cover for the exact location. All of the following checks can be made at the fuse panel. You will need a bright light to see the markings on the fuse panel.
1. In the Bosch world, a terminal designation of “30” means it is un-switched battery voltage. Check for voltage at positions 30 M1 and 30 M2. You should get 12v + at both positions. If no voltage, check the wiring from the battery, the connections to the fuse panel, and the fuse panel itself. You will have to pull the fuse panel up, but disconnect the battery before messing around under the fuse panel.
2. Check for continuity between ground and the temp switch positions "TS" and "TF" on the fuse panel. If you have continuity, the thermo switch is calling for fan operation. If the car is cold, the thermo switch is bad.
3. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle.
4. Connect the jumper between M1 30 to M1, the drivers fan should run at high speed. If the fan does not run, check for voltage in the connector at the fan motor, if you have voltage but the fan does not run, replace the fan motor.
5. Check the passenger fan by connecting the jumper between M2 30 and M2, the passenger fan should run at high speed. If not, the same drill.
6. Next connect the jumper between M1 30 and V1, the drivers fan should run at low speed. If not the resistor or wiring is bad. Check for voltage at the radiator fan connector and then check the resistance across the resistor.
7. Next connect the jumper between M2 30 and V2, the passenger fan should run at low speed. If it does not run, check the wiring and resistor.
If the car is still running hot and the fans are working properly, you have other issues, like a clogged radiator, water pump failing, air bubbles, bad thermostat, or a bad head gasket.
The other positions on the fan relay are:
X = battery power to the logic board in the relay
31 = Ground for the logic board in the relay
AC = AC freeze protection switch
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10-22-2012, 02:51 PM
#8
Advanced
Thread Starter
Thanks for the detailed write up! Just the one fan is running when i turned the AC on and at full speed. I did discover the fan that's not working was blocked by a coolant hose so possibly it was burnt out, but i will def do you're check to know for sure. Thanks again!
