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Porsche944 Porsche944 is offline
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Join Date: Dec 2002
Location: Richmond, VA
Posts: 484
For early cars like your '84, the fans run in several "modes" depending on the status of the ignition, A/C, and the temperature switch in the radiator.

First, both fans should run at high speed with the ignition and A/C on (engine does not have to be running).

Second, one fan should run at slow speed when the ignition is off and the radiator is "hot."

Third, both fans should run at high speed when the ignition on and the radiator is "hot."

If the fans run with the ignition and A/C on, then the fuses, relays and fans are good.

If the fans run with the A/C and ignition on, but do not run when the A/C is off, the ignition is on, and the radiator is hot, then the temperature switch in the radiator is bad.

An easy way to test for a bad switch is to disconnect the wires at the switch and short them together. If the driver side fan runs at slow speed, turn the ignition on: Both fans should run on high.

If it turns out the temperature switch is bad, go for a low temperature switch. Pelican and several other vendors have stock and low temperature switches.

BTW: The cooling systems in these cars are designed such that the fans are not necessary at speeds above about 35 MPH unless the A/C is running.
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Cliff Hipsher
'87 944 India Red
'86 951 Kalahari Metallic
Old 10-13-2003, 07:34 PM
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