Electric Fans always on

[jfitzsi1]

My e-fans are on as long as the engine is running. This is a problem because it doesn't allow the engine to get to full operating temperature.

'01 3.1L. Check engine light is on, took it to get the code read and the guy said something about thermostat Coolant Temp Sensor mismatch???

I replaced the thermostat today and checked the sensor to make sure it was reading correctly. Fans still on.

Any ideas? I'm assuming it is a blown fuse.

TIA

[sad-lumina-owner]

One fan is only supposed to go on when the A/C (Air Conditioner) is running on some Luminas at least. Perhaps it is hooked up wrong, or someone has substituted a different ECM/PCM (car computer) or prom than the one that is supposed to be there.

The fans are supposed to be controlled by the computer. If a computer sensor is disconnected or broken, it is possible that the computer is turning on the fans unnecessarily.

On the other hand, your engine may be running HOT. The temperature gauge in the cab (dashboard) may be inaccurate or malfunctioning, in which case it may be lying about the real temperature of the car engine.

The engine could be overheating if someone put the wrong type of antifreeze in it (suppose it originally had DEX) and this reacted with the old anitfreeze producing a gel or sludge, which inhibits the flow of the coolant.

As a result, the car would overheat and the computer would turn both fans on, but the engine will still not cool down, because the coolant flow is impeded.

Just some possibilities to check out

[jfitzsi1]

Thanks, I'll check that out.

[jfitzsi1]

Well, the fans finally turned off and the check engine light went away. I'm guessing it was a stuck thermostat and the ecu just needed some time before it realized it wasn't stuck any more.