Fan Run-On Problem

Jan 01, 2004 5 Replies
M

I have a 1990 A2 Jetta GLI that has a radiator fan run-on problem. The problem is that the fan is running while the engine is completely cold. It only runs when the control head for the heater/AC is in the



3 A/C positions or the Defrost Position. I assume that this means that I have a faulty high pressure switch in my AC system, as the fan is trying to cool the A/C system to prevent a high pressure head on the AC coolant pump. Where in the engine compartment is this high pressure switch located? I disconnected both of the switches on the A/C line that I thought could be the one and still the fan continued to run. Let me know if you think it might be some other problem as well.

Thanks, Mike D.


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J

No it means it is suppose to run whenever the A/C is on. It is not dependent on engine temp.

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J

I think it's acting normally when the ac is on. When the high pressure switch closes the fan runs faster.

Jo Bo

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R

I agree with the other replies. To elaborate, whenever the ignition is on and the heater control is in a position that calls for A/C, the radiator fan will turn on at the low speed. The exception to this is if the A/C refrigerant LOW pressure switch is open. In this case the A/C is disabled and the rad fan will be controlled by the radiator thermo switch only.

The A/C refrigerant HIGH pressure switch is used to turn the radiator fan on high speed when the refrigerant pressure is too high.

Mike D wrote:

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M

I concur as well. My '91 GTI runs the fan in the A/C position and in the defrost position (which runs the A/C to dehumidify), even with the engine being cold. I believe it's designed to be that way.

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M

Thanks for the input. I was under the impression that the fan remained off until the high pressure switch activated the fan, or the high temperature coolant switch turned on. Great news for me as now I can get back to driving.

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