91 civic cooling. NOT!


What makes the fan go? The fuse checks but the fan is quiet. No juice in the plug there at temperature. Thermostat is new.



Do you mean a radiator fan (engine cooling) or a heater fan (cabin warming) AC Fan #1 (the one on the radiator) AC Fan #2 (see heater fan)???

Assuming you mean radiator fan and not the AC fan or something else, there is a sensor that tells the fan to turn as needed.  It does not operate full time.  The engine may be warm but not warm enough to need the fan.  

Maybe it would help us if you could tell us what you have observed that would make you think there may be some kind of problem.  Tell use what you observed and how that is differs from what you expect.


The cooling fan. I put in a new thermostat.
i tried what I’ve said. The fan dosn’t come on. Temp when driving in Seattle temps is around 200’. When stopped at a light it is 212. I turn the motor off if I can’t go antwhere.


That’s normal operating temperature. Keep in mind 212 is where water boils, but you’ve got antifreeze that gives you many more degrees to go before overheating and boil-over. If the temp gauge isn’t going into the red zone or whatever it has to denote overheating, don’t worry about it. A lot of cars only have high-temp lights-- if you had one of those you’d be blissfully unaware of this issue!

The fan only comes on if your engine gets really hot or if you have the AC on. On a lot of cars in cooler climates, it never comes on. The last car I owned with an electric fan, I only actually had it come on once-- while climbing a hill in Death Valley during August.


That does not sound bad. I don’t know the specs for your car, but 212 is not really high and if you add in the fact that many if not most gauges are not very accurate… Well I suspect you are looking for a non-problem. Is there any other reason you think there is a problem.

What temperature thermostat did you put in? What temperature thermostat is recommended by Honda for your car?

BTW cooler is NOT better.


one way to check this would be to remove the rad cap when cool and look for flow with the engine running. if the antifreeze is moving, then the pump works. i have also removed the thermostat from the housing before, to make sure the pump was pumping.

just to make sure everyone is on the same “page”; you mentioned replacing the thermostat. this WAS the thermostat in the radiator hose housing; not the thermostat for the fan correct?


Did this change from the fan running more often or when cooler? If the fans doesn’t run EVER . . . you have a problem. You should be able to “jump” it by running a test wire from the battery (and a ground) on the two main contacts of the fan motor, to see if the fan has quit on you. Remember it is 17 years old and has been subjected to all kinds of conditions. If the fan will run when jumped . . . there is a relay screwed into the radiator which “senses” the temp of the coolant. Change that sensor/relay and see what happens. Rocketman


“If the fans doesn’t run EVER . . . you have a problem.”

I have a VW Diesel Rabbit for five years before the fan kicked in. I was on vacation driving through the Mahavie Desert when it first came on. I stopped at a rest area and one of the locals congratulated me for being the first Easterner all day to stop and not having overheated trying to run their A/C when it was that hot. I did not want to tell him, but I had run the A/C all day and while it got hotter than normal it never went to the high point. Just not much waste heat in those diesels.


There are two switches which can turn the radiator fan on. One is on the engine, or radiator. The other switch is the fan swith for the A/C and heat in the cabin. Turn that switch to any number, and the radiator fan is supposed to come on. With that switch, it doesn’t matter what temperature the engine is.


Thanks for all the replies.
The thermostat is in the cooling system and is a 180* thermostat. The reason I don’t like it is that I just bought the engine and don’t want to think about doing a head gasket job now. This was specifically not warrenteed. 212 is 18 degrees away from a warped aluminum head in my experience. The normal gauge stopped working after the engine was in so I had to get an aftermarket one.
I have six other cars and trucks and one airplane in my buisiness, so I’m looking more at being preventative. So thanks, I’ll see if I can jump the fan and replace the radiator giz.


Flylow, You didn’t heed any of the advice you were given. Of course, that’s your choice.
An engine coolant temperature of 220F degrees is USUAL and NORMAL. The 180F degrees is just the temperature the thermostat opens to allow the engine coolant to go to the radiator. A properly operating engine system, pressurized to 15 psi, won’t boil over until the engine coolant exceeds 265F degrees.
Rigging the radiator fan to run continuously, or for manual operation, is a mistake. Let the radiator fan switch turn the fan on at 230F, or 250F. Modern engines are designed for this type of operation.


212 is 18 degrees away from a warped aluminum head in my experience.

Was this experience with a Chevy Vega or an aluminum-headed engine of a similar vintage? Aluminum engines have gotten much, much better and are not nearly as sensitive to heat as they once were. Honda knew what they were doing when they installed that thermally-controlled fan. If you wire it to run all the time, your motor will run cooler than it’s supposed to which might lead to lowered efficiency and increased engine wear. On a stock temp gauge that has the operating range divided into thirds, 100C (212F) is usually the lower 1/3rd hashmark-- it’s got a long way to go before it’s anywhere close to being hot enough to damage your engine.