1998 Civic EX overheats at low speed due to radiator fan not running. I replaced the temp switch and thermostat after verifying the fan will run with a jumper at the switch connector on harness. Also swapped relays with no result. I've searched but can't find a solution. Help!

 

Verify the switch opens/closes at temp? Bleed it correctly? (someone quoted "if it seems like it is taking a long time, you are only half way there!)

 

Bleed the cooling system. Does leaving the switch jumped prevent overheating?

 

Yes, if I leave the jumper in the connector it will not overheat. With the temp switch plugged in the Gage can go all the way up and the fan will never turn on. How do you think bleeding may be causing it? Not enough coolant in contact with switch?

 

If you have air in the system the switch will have trouble sending signal.

 

Yes

 

Bingo. That worked. The fan is running. Now I just need to watch it and make sure it's not eating coolant. Thanks guys.