How does the fan circuit work on a 940?

I do question my fan operation while the car is stopped. It will come on for about 10-15 seconds and then go off for maybe 30-50 seconds then come on and go off, etc. Is this normal on a 940 with one electric fan on the engine side of the radiator? I think that if this fan would stay on longer, my A/C might actually blow cold air while stopped.

How does this fan circuit work?

Thanks.

You don't give the car's year, but on my '93 940, the fan does not run continuously. It has a Low and a High speed, both intermittant.

Low speed is controlled by a pressure sensor on the AC condensor. The cycling interval probably varies with temperature, state of AC system charge, etc.

High speed operation can be started by either the thermo-switch on the right side radiator tank, or by a second (higher pressure) sensor on the condensor. These also cause the fan to cycle, turning it off when the temp or pressure drops a specified amount below turn-on level.


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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.