DerekHollister

Alright well I bought a 01 civic and it started to get hot but noticed that the cooling fan wasn't coming on. When you turn the ac on both fan wills come on if I jump the fan switch both fans will come on I've changed the fan switch and coolant temp sensor still doesn't come on unless jumped or ac. What would be causing this issue. In the process of replacing the headgasket on it because it was bad but would like to fix the fan issue while in the process

prodjay10

I believe the temp sending unit and the fan switch are in different locations. One may show hot at the gauge and the other one cool enough to not throw the fan on.

There is a guide in the faq that'll tell you what to check in an overheat condition. If it wasn't a head gasket and it overheated, it'll likely become a head gasket issue. If it's a small leak, you'll see coolant overflowing from reservoir even though it will pass a leak down and compression test as well as a combustion gas test.

However you'll first want to check that list to rule everything else out.

prodjay10

Ha. I just read that you are replacing the head gasket. I'm curious to know if it's possible to test fan and switch by pulling the switch out of the block, or using the old one connected to the harness and in boiling water. If the fan turns on, it may be just what I said.

DerekHollister

Not sure but I've replaced both sensors before and tested it before I tore the motor apart and it still wouldn't come on unless ac was one or jumping the switch. And it's not one fan both fans come on.