986 A/C Fan Operation

[Smitty2001]

HELP!!
I need a clarification. Both A/C cooling fans don't work at low or high speed. The 2 fuses and the 4 relays are in working order after testing Therefore I believe it is the fan resistors or the fan motors or both. I am planning on changing the resistors with the hack (change the resistors with a new resistor 0.5 ohm/100W). Is the resistor's function to increase the speed of the fan when the engine temp reaches a certain temperature? If this is true, will the fans work at low temp even with a bad resistor?

[Marc_986]

I'd start by checking the fans. I guess you can remove the relays and measure resistance at the pin going to the fan (measure against ground). Should be low ohmic. Difference between low and high speed is only that 0.5 Ohm).

The resistors are for low speed operation, where part of battery voltage is dropped across the resistor. Basically the fan operates at half battery voltage or so. High speed is full voltage across the fan.

I ended up taking the crude approach of connecting a battery directly to the connector of the fan. That way you can check both speeds and the difference is obvious (in my case mainly because low speed didn't work).

Also a small tip; spin the fan by hand a good number of turns, there might be too much dust in there for it to operate. Once it turns it will 'grind' the rest of the dust off. That was the case for my high speed operation. Once moved by hand it slowly started picking up speed and after half a minute (or about) it was powerful again.