Hi, I've found that the fan in my Civic comes back on under the following condition:

o Drive car till fan comes on
o Stop car/engine
o Come back in one hour
o Key On Engine Off
o Fan still comes on

This happened today when the ambient driving temp was maybe in the low to mid 70's, by the time I checked again, ambient temp was probably in the high 60s. This occurred another time when the ambient temp was in the low 50s (tops), and I had stopped the engine for at least an hour.

I was about to take out the coolant temp switch out today to check it, but couldn't figure a relatively easy way to get it out. I was hoping I didn't have to take stuff apart to get to it, but it seems to be a pain to get to.

TIA

Edit: Forgot to mention that I'm NOT getting overheating problems. But I HAVE noticed that my fuel economy has gone down of late.

 

When the fan is on with the engine cool, unplug the switch and see if it stops. If it does, you know the switch is bad. If it does not it's probably the relay (on the right fender) getting stuck. Also the fan is tied into the air conditioner control system (if equipped with A/C).

I think the switch is going to be easiest to reach from underneath the car.

Fan stuck on won't noticeably change your mpg, that is going to be a different problem.

 

Yeah, there shouldn't be a relay since I don't have A/C. I'll try it from underneath. I was thinking perhaps the switch remains stuck on until it gets noticeably cool enough to deactivate.

I also figured the fan shouldn't be as much of a factor as my driving habits, dragging brakes, etc.

Thanks for the info.