Checked the forums, some help but still cant find my answer. 1996 Honda Civic DX

My radiator fan won't come on, even with my heater on. I don't have an AC or AC fan so I'm not sure about that one.

-Checked fuses and relays, they are good
-Fan Motor is Good
-Replaced Fan Switch Sensor
-Used paperclip method and that turned the fan on.

What else could it be?

 

Have you replaced the thermostat? If its not opening then that fan won't turn on

 

I haven't replaced the thermostat, the temp gauge appears to be reading properly, so I assume the thermo is good.

 

No, the temp gauge sensor is before the thermostat and the fan switch is after the thermostat. If it doesn't open the fan switch won't get coolant and the fan will never turn on. The bottom radiator hose goes right to the thermostat, there like $11 just replace it and bleed the system. If the fan is good and you replaced the switch i can only think its the thermostat or air in the system but maybe somebody else knows more. Just keep checking back for responses

 

Yeah I just can't see it being the thermostat. If the thermostat wasn't opening the car would be overheating right away. Bottom rad hose gets hot so I know coolant is circulating.

 

Ive heard air in the cooling system can prevent it from working.

Just to make sure I went out and let the car run for 20 minutes with the cap off and the heater blowing. For the record I dont have an AC so im not sure if that does anything. That IS how you let air out of the cooling system right?

 

the fan not comming on has nothing to do with the thermostate

on the thermo housing the will be a plug with 2 wires that is the thermo switch / fan switch
pull the plug off and put a paper clip in there or some thing to short across the 2 wires
in the plug
with the ignition on and engine running the fan should come on
if it does its the fan switch
if not look at the fan relay and also the fuse

 

I did that, and the fan came on. So I,

-Replaced the fan switch
-Ran the car with rad cap off (with heater on but no AC system so I'm not sure if it does anything) to bleed any air in cooling system..Fan never came on but got to operating temperature
- Drove around for about 15 minutes, car didn't get hot, but I don't think the fan ever came on, and it wasn't on when I got home and checked under the hood.

 

just let it run sitting still it should come on
it can take a while depending in the outside temp
if it still doesnt check your fuses
and then check the relay for the fan

 

Let it run for 45 minutes, fan never came on and it stayed at normal temp. It only gets hot when in stop and go traffic though.

 

with the rad cap off does the water flow all the time if so it could be the thermostate is
jammed open and not allowing the system to heat up enought to turn the fan on
another thing you could try is looking to see if the fan switch connection is loose in
the plug
you can also do this test without the motor running
with the fan switch removed but pluged into the loom
lower it into a cup of boiling water while the ignition is on
this will simulate the car being hot and the switch should turn the fan on

oh just to make sure we are talking about the same part Fan switch
its located on the thermostate housing with 2 wires
only asking as not to get confused with the ECT or the gauge temp sender both are located on the head below the dizzy

 

Yes I am sure I know which one is the switch

I'm not going to try that boiling water stunt - too much work and too risky

I know the thermostat opens and closes because it runs hot sometimes in stop and go traffic but cools down when I get at higher speeds. All of the temp readings seem logical, so Im ruling out the thermo.

I know the plug isnt loose, I can hear it snap in.

I don't know what you mean by "does water flow all the time?"

 

when you look into the top of the rad with the cap off you will see the water flow
if it does this when the motor i cold then the thermostate is jammed open
this can cause the motor not to come up to the temp required to turn the fan on via the fan switch

the water test isnt risky
just boil some water and pour into a cup then lower the fan switch into it as above post
with the ign on but the motor off the fan should come on if it doesnt then the fan switch has failed to activate when hot and needs to be replaced
the test will prove if the switch works or not
as it should turn on at appx 80c or 176f
with a just boiled cup of water you will be above that temp and the switch should activate the fan