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I wouldn't Posted by Ari [Email] ![]() ![]() In Reply to: cut out the fan relay entirely...just use the switch., SloopJohnB, Wed, 14 May 2008 06:23:29 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The thermoswitch in the radiator is designed to drive a relay, which is a low current device. The radiator fan is a high current inductive load (close to 30 amps) that puts a big strain on the contacts. That's why they run the fan through a relay, because relay contacts can be designed for big current loads.
Yes, you can just use the thermoswitch, but you'll have to do some re-wiring. The switch is a closure to ground; the fan is expecting 12 volts and already has a ground. So you'd need to wire the high side of the fan to the fan fuse and wire the thermoswitch into the low side of the fan.
But I expect you'll be buying a new thermoswitch soon. The high current of the fan, especially when the switch opens (back EMF is nasty) will chew up the thermoswitch contacts. There's also a good chance that the thermoswitch would fail shorted, which would leave the fan on all the time.
I'd go with the change listed on the Townsend website. It uses a relay to switch the big load as intended, and cuts off when the car is off.
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