Overheating '86 4Dr Civic

[Si_Dude]

I have a Overheating '86 4Dr Civic auto (no fule injection)....temp dial goes to very region (not red)....fan does not come ON....I can force the fan ON by activating AC switch, then fan goes ON, AC works and engine cools down to normal. Looks like cooling fan does not turn ON under normal conditions. Checked the factory manual. There is a "termo switch" in the radiator that could be bad. How do I test it? How easy is it to replace? Also, there is a "temp snsor" somewhere....where is it? Any ideas on how to track down and fix this fan problem?? Any help appreciated...Thx

[johnboy27]

The thermo switch is in the bottom of the rad right below the fan. All you have to do to get the fan to stay on all the time is to unplug the swtch and then use a wire to cross the two plugs.Tape the wire in and the fan shoul;d come on as soon as you turn the key on.

[Si_Dude]

Thx...johnboy27....I will try it this weekend...

[Si_Dude]

I managed to pull the wires on the thermo sensor on the "passenger side" and jumped them. Sure enough, the radiator fan came on as expected. Looks like this thermo sensor switch has gone bad.

While I was at it, I also noticed that this '86 Honda radiator has TWO thermo sensor!! There is another thermo cooler on the "driver side"??
The FSM only shows only 1 thermo sensor on the "passenger side" for the '86 Honda Civic (4DR, no fuel injection) radiator.

Does anyone know what the other thermo sensor does???

Thx for all the help...

[johnboy27]

Are you sure? The drain plug is on that side I believe. I can't see it being another sensor unless maybe your car is an auto and it is a sensor for the tranny fluid or something.
Oh and by the way,there is no point in changing the thermo sensor,I have never had one actually work for me.I have changed them out for a known to be working one only to find that it wouldn't work anyway,even though crossing the wires does.

[jdub518]

that totally worked. Saved alot of money, and time! Thanks!!

[johnboy27]

No prob fella's,that's what I come here for.To be helpful and to get help.