Fan comes on even if car is off - Pontiac Grand Am

I recently bought my son his first car, a 1998 Pontiac Grand Am - got it from a small car lot and thought it would be a good “beater with a heater” for his first go around.

We recently pulled the car inside our garage since the temps dropped (about 2 weeks ago) and ever since then, I had been hearing a fan-like noise coming from the garage area, about every 30 minutes.

I went out there today and stood until I heard the noise again and sure enough, 30 minutes after hearing it earlier, it happened again and it WAS coming from his car, under the hood. It almost sounds like someone turning on a leaf blower for about 5 seconds and shutting it back off. Mind you, this car has only been driven twice since we bought it in September; on the way home and once around the block because he’s not able to drive yet. He does go out and starts it once a week, but it has not moved since being brought home.

Why on earth would this car, which does not move and only is started once a week, be making this noise? I can only guess it’s the engine fan popping on, but why? It’s not turned on, the ignition is off, the AC/heat dials are all set to “off” but like clockwork, every 30 minutes this fan comes on.

I am not making extensive repairs to this vehicle, but I also don’t want it burning down my garage if it has a short!!

Any help you can provide, is most appreciated.


Electric fans kick on when it senses the water temp is at a certain temperature or higher. I suspect it might be the temperature sensor is faulty. If the engine is hot (like right after a drive), then the fan will cycle on and off until the temps go down.

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Even if the car hasn’t ran in almost a week? It’s been sitting for about 5 days since it was last started, and even then, we only left it running about 10 minutes.

The powertrain control module controls the cooling fan relay.


The problem may be with the PCM.


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