I have a 95 civic dx auto, and ran into some heating issues about a month ago with a leaky radiator and boiling fluid. Turns out that my radiator fan does not turn on as well. The motor is fine, the fuses are new, and the electric wiring doesn't seem to have any problems.

I already replaced the radiator, but it still overheats. Is the overheating due to the fan not working, or something else?

 

If the fan isn't working, yeah... I'd have to say I think that's the problem.

You said the fan motor is fine, all fuses and wires look good but the fan doesn't come on?

My guess is the relay (on the electronics bank by the battery) isn't telling the fan to come on. The temperature sensor could be faulty too.

Best thing to do is look at the owners manual to find out which relay you need to be looking at then see if there's any obvious damage such as burnt marks or melted plastic. You might be able to test this theory by using a relay from a nonessential system in the car and if it turns out the fan comes on when you put a relay in that's what you need to replace. Assuming the engine is hot and the relay is the problem you wouldn't even have to have the engine running to see if the fan comes on as it should upon substituting another relay.

 

It seems like there is only 1 cooling fan relay. Would the thermostat have anything to do with it? The relay looks fine and everything seems normal.

 

Did you check your thermostat too? Thermostat could be stuck closed.

One person said to check to see if you have a bad thermostat is to get an old pan, fill it with water and set the thermostat in the water. Boil the water and the thermostat should open. If it doesn't there's your problem. Also do not reuse the pan for food anymore, throw it away or label it "Not for Food use".

 

Would a stuck thermostat cause the radiator fan to not turn on?

 

if it's not getting hot coolant from the engine it will not turn on.

When the thermostat opens it releases the hot coolant from the engine which passes the thermo switch which turns on the fan (if memory serves me right).

 

warm up car, check upper hose and lower hose. one should be hot and the other should be cold. if thermostat is stucked closed, the water pump still pumps rights? then your coolant reserve should overflow because thats where the coolant will go or wherever the coolant can find its way out (weak point).

 

So I changed the thermostat, the radiator thermoswitch with still no luck. Other possibilities?

 

Did you make sure you put it in right?

The only other thing I can think of without seeing it is the temperature sensor is bad.

Have you tried replacing the rad cap?

 

im not trying to post on someone elses question, but i have a simalar question, my car overheats and i have to shut the car off and turn in back on without starting it and let it sit for a few minutes for the fan to turn on, could that be due to a stuck thermostat?