My electric fan on my '93 GS300 has not been working for some time. I thought it was the switch in the bottom of the radiator so I installed a new one. The fan still didn't come on but I found out when I remove the connector to the switch and the ignition is on the fan turns on. I reconnected it and the fan immediately shut off. Obviously the fan is good so what could be wrong? Wiring seems fine so the only other possibility seems to be the relay or some type of short.
Any help appreciated.

 

Check the 30 amp fuse?

 

The ECT switch should have no continuity when the car is hot (which is why the fan turns on when the connector is pulled), and the switch should close when the engine is cool. Obviously the fact that the fan runs when the connector is pulled indicates the fuse, relays, and fan are all OK. Still indicates a bad switch.

Try leaving the switch plugged in, and turn the A/C on full cold (65 deg). The fan should come on then too.

Everything points to bad switch. I would pull it and test the continuity when cold, then put it in some boiling water to make sure it changes state.

 

Yeah I misread the post. The electric fan only comes on when it reaches something like 210 degrees or if the AC is turned on.

 

I did that and confirmed the new switch is working. I will install it now. I wanted to make sure I needed a new switch because the best price I could find was $72. I assumed the circuit was wired the other way and the switch would close, not open when hot. Any idea why it is wired this way? The only reason I can think of is so the fan stays on when you turn the car off.
Anyway, mystery solved, thanks for the help.

Ozzie

 

Yes, those switches are expensive. I needed one for my car recently and could not find a better price. I wound up pulling one out of a late model junkyard Camry instead.

I have no idea why the switch is designed that way. I also would typically expect it to close when hot.