Just bought a 99 Corolla for my daughter and both fans in front of radiator come on when ignition is engaged with engine cold. Assume it must be relays or coolant temp sensor, is that correct thinking? The temp sensor to me looks like it is behind the intake tubes and quite hard to get to. Anyone have any experience with this situation and could offer some guidance. Much appreciated. Thanks..
Is the air conditioning on? The fans come on when you turn the AC on.
No,the fans run whether the a/c is on or not.
Chances are the thermostat(s) went bad and the person wired up the fans to run whanever the ignition is on. I sorta did this with a 240SX I had; the damn thing would keep overheating in town with the AC on. Turns out the extra fan for the AC wasn't turning on, so I wired it to turn on whenever the AC was on (it was supposedly controlled bu a thermostat.)
Check the wiring near the radiator and I thnk you'll find it kludged...
Took a look at wiring but doesnt look like it's been messed with. Looks like factory connectors into wiring harness across front. If these fans stay on all the time will they wear out too soon or should I just not worry about it. Any ideas? Thanks again.
It will take a little longer to reach operating temperature, and the fans may crap out sooner than expected. I would guess the thermostats have shorted, but it is odd that they both would at once! No jumpers or splices, eh? What I did with mine was jumpered one connector, so unless you knew what you were looking for, it wouldn't seem out of place.
Somewhere near the thermostat housing is the engine coolant temperature (ECT) switch. Carefully remove the connector, and with a cold engine and ignition switch on, you should have continuity between the 2 terminals on the switch. If there is no continuity with a cold engine and ignition on, the switch is bad. By the way, the fan should stop when you unplug the switch.
I'll take a look at it again tomorrow when it's light again. The engine temp guage seems to come right up to middle range after just a few minutes of running from dead cold. Thanks for the suggestions.
Ok I'll give it a try tomorrow when I get home from work. Thanks
Nope. The sensor on the thermostat housing is a single wire. Fans stay on when I unplug it.It was a tough one too because it is under the alternator. Very cramped space.Another sensor that is a few inches over is also a single wire. Cant get to it because it is behind the intake tubes. Found a third sensor into the block that is two wires( or maybe three). Its more over by the throttle body, air filter housing area. I had to take off the air filter housing to get to it. It shows I guess about 2300 ohms cold and around 500 ohms when run for a few minutes. Fans still stay on even if removed. Course car runs rather rough unless I leave it pluged in.Thanks for the suggestions.
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