Which temp fan switch?
11-19-2012, 01:53 PM
#1
Pro
Thread Starter
Join Date: May 2009
Location: If it's the wknd, I'm at a track...
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
Which temp fan switch?
86 951. In the last couple of days the radiator fans stopped turning off with the car/ignition switch. I haven't tested yet but I'm figuring the temp fan switch. Pelican has 3 different temps for the switch; 167, 199 & 215. What are the advantages/disadvantages to the various temps?
Anything else I should be looking at? FWIW, pulling the fan relay after ignition is off but fans are still running does nothing.
TIA
Anything else I should be looking at? FWIW, pulling the fan relay after ignition is off but fans are still running does nothing.
TIA
11-19-2012, 04:20 PM
#2
Former Vendor
The stock switch for the turbo is supposed to turn the fan on at about 185ºF. A lower temperature switch might be better in a hot area of if your car is tracked.
11-25-2012, 07:47 PM
#4
Three Wheelin'
The fans are not dependent on key position and can run at any time. Do they run the battery down? Check out Clarks Garage or use this procedure to narrow down the problem.
During normal operation, and you have the factory rated thermostat, the coolant temperature gauge should read at or near the lower white line (80 degrees C) and will creep up to the mid-point between the upper and lower white lines when sitting still in traffic. The upper white line represents 100 degrees C. If the temperature normally runs above the mid-point, you need to investigate immediately.
There are several temperature ratings of the thermo switches, so it is hard to say at what point they should turn on for your car. If they are not both running at high speed when the temperature is above 90, you might have a 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 fuses first, then 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. Disconnect the thermo switch connector at the radiator, and jumper terminals 2-3, you should have continuity at TS. Jumper terminals 1-3, and you should have continuity at TF.
4. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle.
5. 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.
6. 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.
7. 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.
8. 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
During normal operation, and you have the factory rated thermostat, the coolant temperature gauge should read at or near the lower white line (80 degrees C) and will creep up to the mid-point between the upper and lower white lines when sitting still in traffic. The upper white line represents 100 degrees C. If the temperature normally runs above the mid-point, you need to investigate immediately.
There are several temperature ratings of the thermo switches, so it is hard to say at what point they should turn on for your car. If they are not both running at high speed when the temperature is above 90, you might have a 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 fuses first, then 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. Disconnect the thermo switch connector at the radiator, and jumper terminals 2-3, you should have continuity at TS. Jumper terminals 1-3, and you should have continuity at TF.
4. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle.
5. 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.
6. 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.
7. 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.
8. 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
