95 Civic overheats when not moving

My 95 Honda civic overheats when the car is not moving. It only seems
to over heat after I drive the car on the freeway. I've let the car sit
for 20 min running and the temp stayed fine. But if I got about 5 miles
on the freeway and get of as soon as I'm not moving it over heats. I've
noticed the fan does not come on when the temp goes up. The fan only
comes on at random times, like when the car is off. I replaced the
thermostat today but that did not change anything. The water pump and
radiator were changed about a year and a half ago. At this point I have
no idea what to try. My next step is taking it to a shop if I can't
figure it out.

 

It sounds like the relay for the fan is corroded. It shouldn't deliver
power when the car is off.

 

Sounds like either your fan is not cycling properly.... or your
radiator is partially plugged up and is having flow problems. By the
vintage of the car... my guess is that your radiator has blockage due
to mineral (lime) build-up. If you take your radiator cap off (when the
engine is cold of course!) and stick your finger down to the core
surface... when you rub across this surface and pull you finger out...
is your finger all white? If so, that is mineral sediment. There are
ways of extracting the sediment without replacing the radiator. Email
me for details.

Professor
www.telstar-electronics.com

 

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Cold engine. When you open the rad cap, it has to be full to the very
top, and the reservoir should be full nearly to the MAX line. Don't put
any tap water in system, that's called Hondacide. Since the thermal
sensors have to be immersed, your system won't work right unless it's
full to the top.

'Curly'

 

How right you are... never a good idea to put tap water in any cooling
system because of the mineral content. Always use distilled water. It's
reasonably cheap and will help make your cooling system components
(radiator and heater core) last longer.

Professor
www.telstar-electronics.com

 

Just a reminder as you follow some of the advice so far given in this thread
(which all looks familiar and sound to me):

My 1991 Civic's fan takes as long as 40 minutes with the car idling to kick
on in 70 degree F ambient temperature, from a cold start. All operates fine
on my car.

 

wrote in

Sure sounds like your fan switch relay is bad. Common for your year.

http://www.tegger.com/hondafaq/overheating/index.html#nofan

 

Looks like I got it working. I replaced the Fan Switch Relay that was
on the housing for the themostat and it apears to be fine now. Thanks
everyone.

 

Well it was working till the other day. It only over heated once since
I replaced the fan relay. You guys said there was a fan relay and
switch where are they located? I replaced the one on the thermostat
housing.

 

The radiator fan relay is located inside the under-hood fuse relay box.
The relay is triggered by the Engine Coolant Temperature switch (ECT)
mounted on the thermostat housing. The ECT operation is dependent on
proper fill/bleeding of the cooling system...HTH