Should the electric fan continue to run when the switch is turned off?
10-01-2002, 09:05 PM
#1
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Should the electric fan continue to run when the switch is turned off?
Mine doesn't and the fans on most if not all cars continue to run until the radiator cools down.
10-01-2002, 10:21 PM
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Mine did that too, Jim. Bad fan switch, you can jumper it by connecting the two wires together, to help the a/c until you get the part. This way it runs whenever the ignition is on.
This fan just helps the a/c stay cool, and cools the engine bay after a good run. The switch is cheap but you'll have to change your coolant-
Normy!
'85 S2 5 Speed
This fan just helps the a/c stay cool, and cools the engine bay after a good run. The switch is cheap but you'll have to change your coolant-
Normy!
'85 S2 5 Speed
10-02-2002, 12:21 AM
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On the pre-S4 models, the electric cooling fan is operated by three (5-speed) or four (automatics) sensors.
A coolant temp sensor located in the lower forward face of the radiator end cap. This sensor is open below the set coolant temp, closed above that temp. You can buy sensors with different trigger temps. To test the switch, pull the harness off, check continuity of the switch. Should be open when the radiator is very cool, closed when the radiator is above the trigger temp. To test the fan circuit, pull the harness off, turn the ignition switch on, and short between the contacts in the harness. The fan should run. If it doesn't, check fuse # 29 (25 amp) or relay XVIII.
A freon temp sensor located on the stem of the receiver/dryer. This sensor is open below the set temp of the freon in the receiver/dryer, closed above that point. Tests are the same as for the coolant temp sensor. This sensor does not appear to be very effective on most cars.
A transmission fluid temp sensor located on the torque convertor, on automatics only. This sensor is open below the set temp of the transmission fluid, closed above that point. Tests are the same as for the coolant temp sensor.
These three temp sensors work by grounding terminal 85 of relay XVIII, triggering the relay. The relay contacts are fed from bus X (ignition on) thru fuse # 29 to relay terminal 30, and the output contact (terminal 87) runs directly to the fan, running the fan at full speed.
In addition, there is an air temp sensor mounted on the intake plenum. This sensor is fed power thru fuse #23 regardless of ignition switch position, and is open when the air in the intake is below the set temp, closed above that temp. When the sensor closes, power is fed thru a resistance to the cooling fan, causing it to run at a lower speed. This is primarily for cool-down after engine shut-down. It will run only when the engine is pretty hot on shutdown.
A coolant temp sensor located in the lower forward face of the radiator end cap. This sensor is open below the set coolant temp, closed above that temp. You can buy sensors with different trigger temps. To test the switch, pull the harness off, check continuity of the switch. Should be open when the radiator is very cool, closed when the radiator is above the trigger temp. To test the fan circuit, pull the harness off, turn the ignition switch on, and short between the contacts in the harness. The fan should run. If it doesn't, check fuse # 29 (25 amp) or relay XVIII.
A freon temp sensor located on the stem of the receiver/dryer. This sensor is open below the set temp of the freon in the receiver/dryer, closed above that point. Tests are the same as for the coolant temp sensor. This sensor does not appear to be very effective on most cars.
A transmission fluid temp sensor located on the torque convertor, on automatics only. This sensor is open below the set temp of the transmission fluid, closed above that point. Tests are the same as for the coolant temp sensor.
These three temp sensors work by grounding terminal 85 of relay XVIII, triggering the relay. The relay contacts are fed from bus X (ignition on) thru fuse # 29 to relay terminal 30, and the output contact (terminal 87) runs directly to the fan, running the fan at full speed.
In addition, there is an air temp sensor mounted on the intake plenum. This sensor is fed power thru fuse #23 regardless of ignition switch position, and is open when the air in the intake is below the set temp, closed above that temp. When the sensor closes, power is fed thru a resistance to the cooling fan, causing it to run at a lower speed. This is primarily for cool-down after engine shut-down. It will run only when the engine is pretty hot on shutdown.
10-02-2002, 08:20 PM
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Thanks Wally,
This will help me to check out my newly acquired 84 928S auto I purchased a couple of months ago. I found this Discussion Board a little late to use the information for my purchase, however I am very happy with my 928 and this forum. I am gaining wonderful insite to many issues. I look forward to the many years of conversing with the top quality people that have chosen to own Sharks. Again Thanks to all the owners that take the time to post information!
This will help me to check out my newly acquired 84 928S auto I purchased a couple of months ago. I found this Discussion Board a little late to use the information for my purchase, however I am very happy with my 928 and this forum. I am gaining wonderful insite to many issues. I look forward to the many years of conversing with the top quality people that have chosen to own Sharks. Again Thanks to all the owners that take the time to post information!
