When replacing the radiator in my daughters 96 Civic I also replace the hoses, thermostat, etc. An online manual mentioned using a bleeder screw to help bleed off the air, but i don't find that screw on this one. After feeling I had the motor sufficiently up to temp and the bottom hose was hot I found the fan wouldn't come on. I replaced the CTS with no luck. But....after jumping the two pins on the connector, I find the fan runs with the key on. Wouldn't that indicate a bad sensor(Which I just replaced) or am I missing something obvious?

Thanks,
olcurt

 

The 92-95 Civics have a bleeder bolt for the cooling system that is missing in 96-00 Civics. For the latter, you bleed the system by turning the heater to max heat (not blower), topping off the reservoir and radiator with coolant, and letting the engine idle with the radiator cap loose until the radiator fan turns ON twice (takes 15-30 minutes). Then repeat the coolant top off.

Yes, if the fan turns ON when you jump the wire harness connector to the switch on the thermostat housing, then the switch itself is bad.

 

Maybe I didn't let it run long enough, but it had probably been a good 20 minutes and the air coming out of the heater vents was very warm. Although I will admit, the temp gauge hadn't moved even to the midpoint. The coolant in the radiator was starting to steam and that worried me, so I shut down.

 

Well, the apparent overheating may have been caused by the failure of the radiator fan to run. Or you possibly have air trapped in the cooling system. Maybe you should bleed the system with the coolant temp switch connector jumped and just let the engine idle for 20 minutes.

 

Sounds like a good idea. Hopefully, I can get it back running with a coil and then fix this. I found a lot of variations at autozone for the temp fan switch and the first didn't match at all. I am wondering if a parts run to the local Honda dealer is in order for tomorrow. Maybe I have the wrong part for the fan switch. I'll check tomorrow. BTW, I'm really glad you were on here tonight. I'm off to a good start for tomorrow. I'm off work for the day, and hopefully my daughter will have her car running before I leave for Alabama later in the day for a soccer tournament. I heard her tell her boyfriend with a giggle that she wasn't sure I knew what i was doing. She has watched me rebuild my grandpas 66 chevy pickup from scratch, but I think she has little faith in my work on a honda. Little does she know, I am smart enough to ask for help!

Thanks for all your help!

 

I am always glad to help out. Good luck with the fix. I'm sure some day your daughter will recognize your many talents. Also have fun with the soccer tournament. Just post any questions that come up, and we'll try to help you out.

 

You have to idle the engine for quite a while before the fan will come on. The switch is activated by the temperature of coolant leaving the radiator, so even after the engine is at normal temperature, the radiator has to heat up too. The fan should come on though before the temperature gauge moves above the normal mark.

The part to ask for is the "coolant temperature switch". There are 3 sensors that measure coolant temperature. The "switch" controls the fan. The "sensor" tells the ECU if the engine is warmed up or not. The "sender" drives the gauge on the dash.