Cleft_Asunder

iTrader: (1)

My radiator fan hasn't come on for over a year, at least from what I know. I'm not experiencing any overheating strangly. I'm running Honda anti-freeze.

I just shorted the radiator fan to the battery and it starts fine. I found a troubleshooting guide for this, but the author wrote it poorly. Here's where I'm confused:

"Thermo sensor check

Short the contact on the connector going to the thermo switch to ground. This connection goes to the fan relay. (WHAT???? I don't understand what you're trying to say. Do I do this when the car is on?)

If the fan turns on, your thermo switch is most likely bad.

If the fan does not turn on and the fan was not turning on with the AC running, your relay may be bad."

Cleft_Asunder

iTrader: (1)

Wait, is he saying that I should stick a wire from the negative into the positive of the ECT switch? I think so...

Cleft_Asunder

iTrader: (1)

Yup, fan come's on when I short it. I already checked the relay, fuse, and motor before this so it was down to the wiring or ECT switch. Should I buy a stock ECT or should I go for a lower TEMP switch?

Here is the troubleshoot guide: http://www.tegger.com/hondafaq/overh...heating-index/

tuningmycivic

iTrader: (11)

switch the car on and short the two terminals of your ECT sensor connector. if the fans turn on, everything else is good. replace the switch. if not, check the relay in the underhood fusebox. I had a problem with my fans not turning on at all. it turned out being the switch after I had replaced the thermostat.

the only way to check the switch is to heat it up to 199 degrees (according to certain online manuals) and check for continuity. as i'm sure you imagined, it would be quite hot and not easily handled at that temp.

Cleft_Asunder

iTrader: (1)

Mine failed after I installed a new thermostat too, and radiator flush. Why would it do that??

Do you know if I need to drain the radiator fluid before thermo switch removal/install?

gearbox

iTrader: (95)

just replace the switch, sounds like a random fail

Cleft_Asunder

iTrader: (1)

Yeah but how do I know the switch is bad for sure? I NEVER overheat. It was 85 today, and I did all city driving. Temp is totally normal. Fluid level is perfect. How do I know I'm even reaching 194 degrees?

I don't want to remove the radiator fluid if the switch is still good. But again, the fan does not turn on when I hit A/C. Are they both supposed to turn on or not?

Cleft_Asunder

iTrader: (1)

Source:

http://www.hondacarforum.com/honda-3...5-civic-2.html

"I just replaced the thermo switch, and the radiator fan *still* doesn't come
on, even with the AC switched on (the AC compressor fan on driver's side
does come on).

I measured the new thermo switch by putting an ohmmeter across the terminals
and lowering it into a pan of boiling water. After the switch closed I got 1
ohm of resistance. The old thermo switch read 8 ohms. So I guess it was bad?

I'm not sure what else it could be.... shorted one side of the thermo switch
connector to ground does make the fan come on while the engine is running.
There's nothing else in the circuit as far as I know.

The temp guage never rises above 1/3 level (so far). Tegger, you had asked
about the heat output in the passanger compartment. At times, it seems to be
normal. Other times, it seems to be cool, even when the temp setting is over
at max. Could this be due to a bad thermostat or something else?"

Reply:

Personally, I think you're barking up the wrong tree here. 1 ohm or 8 ohms
means nothing. If the temp gauge never gets past 1/3, the rad fan WILL NOT
START NO MATTER WHAT.

If you simulated the heavy stop-and-go traffic like I said for AT LEAST 5
MINUTES, and the temp gauge DID NOT RISE, then your engine IS NOT HEATING
UP ENOUGH to make the fan come on.

I do believe you have a bad thermostat. Replace with new **OEM** for $20,
then report back, BEFORE you spend bigger bucks on the thermoswitch.

gearbox

iTrader: (95)

both fan should come on with a/c in use, ALL THE TIME otherwise the condenser does not get enough flow and your air wont be as cold. radiator fan only comes on periodically while driving, usually for 10 seconds at a time. our civics do not rely as much on the fan as other cars. i saw an older ford come in with broken radiator fan and the car overheated so bad, the entire overflow tank was empty from coolant boiling off. ive rarely noticed the fan kick on unless the car is at idle in warm weather 80F+ but it should come on. after driving for a while, park the car in the sun and wait 5 minutes at idle. the fan will come on at least once if its above 80F outside i promise. if it doesnt then you have a problem

Cleft_Asunder

iTrader: (1)

Yeah but two people on that board reported no radiator fan with AC on, and they aren't overheating, and neither am I so that's 3. I think it depends on the civic.

I will see if it comes on in really hot weather. I will attach some tape to it maybe to see.