aux fan on all the time.

[quote:3dfa507d09="civic1991dx"]1991 Honda Civic dx 145,000 miles

someone gave me this car. they said it used to run fine but then it started overheating constantly and they were getting ready to tow it to the junk yard.

i looked it over and realized the thermostat was stuck closed and the aux fan motor was burned out. i droped in a new thermostat and tried running the car, and it really seems to run great until it got hot... which never seemed to happen as long as i was moving. And there did not seem to be even a hint of white smoke in the exhaust and it didn't loose any coolant fluid either. i replaced the aux fan, flushed out the cooling system and everything seems to work good, except the aux fan is now on all the time (probably why the old one burned out). it took me forever to find the thermo switch since it was not on the radiator, or the thermostat housing, but in an obscure place on the back of the engine block (not mentioned in my repair manual). the thermoswitch has 2 leads. if i pull the contacts from the thermo switch, the fan stops. when i plug it back in, the fan is on again.

it is a special order thermoswitch for $50. how can i be sure it is the thermoswitch and not a relay?[/quote:3dfa507d09]

Hello !!

Well... you already tested!

that`s the way to test the thermoswitch...

if the problem was a relay "stuck closed" disconnecting the thermoswitch didn`t make the fan stop...
I mean the thermoswitch its "closed" all the time and sending a signal to the relay to close the contact.

Anyway check a junkyard probably you can get an used one in good shape for a way less money!

good luck and thanks a Lot for your Donation!

we appreciate that!

Any other question do not hesitate to ask!