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Full Version: Radiator fans on with a cold engine.
6G Celicas Forums > 6th Generation Celica > Engine/Transmission/Maintenance
I've noticed my radiator cooling fans will come on as soon as I get my Key to ACC.
Research so far suggests that it could be the fan switch or the fan relay.

Took the relay out and it makes a click sound on 12v power from a battery; but when it's in a clicked state, and I hook up the ohmmeter to the other 2 poles, it shows no connection. So my relay is bad and I got another one on order from ebay.
The fans though, are still running when the key goes to ACC even with the relay unplugged sitting on the table.

Is this normal in the case of a failed relay? Would the car's electrical system handle it that gracefully when a relay fails?

edit: Just realized I maybe should have posted this in the Electrical Forum, always feel like that is for interior I guess. Mods, feel free to move this post if It should be there instead.

edit2: Doh! Just learned that this relay is normally closed (Iguess how it does graceful failure), and tested it *without* the 12v and it works. So thinking it's the radiator fan switch stuck in the on position. Oh well, at least I only spent 6.50 on the replacement relay.

edit3: Ok, upon looking at it all again, the number 1 fan is off when its relay is pulled. So at least it no longer appears the relays have been bypassed.
Edit 4: Got the fan switch disconnected. The Ohmmeter shows continuity on a cold engine. Which tells me that the fan switch, at least at low temperatures, is doing what it's supposed to do. Not quite sure what to test next.

There is a possibility that the fan switch has been bypassed. Can anyone else tell me if their fans come on when the key is in the ACC position with a cold engine? Could be some kind of feature of the ECU (to reveal a fan fault before it becomes fatal perhaps) and I'm just chasing my tail.

just pulled the A/C single pressure switch plug and ran a wire between terminals 2 and 3 on there, turned the key to ACC, and no fans. So probably that switch is stuck in the open position, so that's the one I should try to replace.
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