1992 Civic DX, automatic transmission, 218,xxx miles

I've had the car close to a year and I have never heard the radiator fan turn on. It has never overheated or burned/leaked coolant so I kept putting it off.

I pulled the thermostat switch plug off and jumped the plug end and the fan turned on (with key in ACC). Followed the suggestions here and replaced the thermostat switch, left the car on for close to 30 minutes and the fan still hasn't turned on. Driven for three weeks and still no fan action.


Will my passive grandpa style driving keep the radiator fan from ever coming on? Car does not like to be in Drive after warming up and sitting stationary so I was thinking this might be related?? Timing was checked per manual (2 pin ecu plug was jumped, car in neutral and done with the engine warm)


I have followed this thread (https://honda-tech.com/honda-civic-d...rking-2580655/) before it was locked and have done all suggestions/steps listed by the service manual as posted by RonJ, bleed the coolant system and the fan will still only turn on when I jump the plug.

The resources in the FAQ only mention fixes if the car overheats, which mine does not. Thanks

 

Sorry I can't help but you just brought up an issue that I suspect I'm having. Fan never comes on. Mines a 93 Civic DX manual transmission. Where's the thermostat switch located? I need to do this. BTW, I'm trying to learn how to remove the head right now to replace a head gasket and my fan is suspect. Fix it right away!

 

The fan switch is located on the thermostat housing, there is no thermostat switch.

Mike, I wouldn't sweat the radiator fan not coming on. My beater fan never comes on and as long as its not overheating.

The no start when it gets warm could be a lot of things. Injector heat soak, main relay, etc.

 

From the other thread that I linked http://i267.photobucket.com/albums/i...cture_2825.jpg

 

I'm more worried about the low idle at stop lights/intersections etc. The plugs/wires/valve cover gasket are all brand new. Timing, to the best of my limited ability is correct. I do not have a no start when warm issue, just a very low idle in drive when stopped while warm

 

I'm going to install a temporary manual switch for the fans to see if the fans engaging will increase the RPM at dead stops when warm and then reply but I don't see that as a solid permanent solution.

 

You probably have an air pocket, bleed the coolant.

For low idle, if everything else checks out check the temp sensor on the head.

Sometimes you might need to re-adjust your idle speed again.

 

Thanks for your reply and I notice that I did fail to mention that the car had a low idle before swapping the thermostat but I will bleed the coolant again, never hurts. I will check the temp sensor on the head( the only single wire that connects just underneath the distributor).

 

Bleed coolant first before messing with the idle.

 

The coolant has now been bleed 3 times, I just drove 200+ miles, mostly highway and the fan did not engage

 

Exactly how did you bleed the coolant? Exactly what makes you think adjusting your idle will have anything even remotely to do with your radiator fan?

The single wire sensor under the distributor is only for your gauge cluster, and has absolutely nothing to do with your radiator fan.

 

Exactly as NAR stated, the one wire under the head switch does nothing for your fan.

The fan's thermo switch is on the thermostat housing if I remember correctly.

The two pin sensor on the head in front of the one wire you mentions is the Engine Coolant Temp sensor for the ECU.

The thermo switch is your likely culprit and I think there is a hot water test you can do with it and a digital multimeter.

Your idle when warm if in the USA should be around 650 rpm which will be barely above the first mark on your tachometer.

 

The coolant was bled following honda procedure as stated in my honda manual, and again as posted in the other thread.

The checking of the idle was to try to help diagnose the very low engine RPM in park while at a dead stop after the engine has warmed up. Having the wrong base idle will give me problems at idle. Makes sense right, or am I way off with that?

I'm fully aware that the single wire under the distributor is not in any way related to the radiator fan functioning. I just didn't want to come off rude to the poster of the suggestion.

 

Correct, the thermo switch is threaded into the thermostat. It has a single 2 wire plug and the switch completes the circuit at temperature and allows current to flow from one wire to the other. This is why removing the plug and having a jumper wire between the two pins will turn the fan on, assuming your fan relay is good.

Again, as stated in the OP the thermostat switch has been replaced and the fan has still not turned on during driving. But I will look up how to test it out of the car, pull it out and "bench test" it.

The idle was checked and found to be in spec. I'd have to look it up again but 650 sounds right.

 

Might want to pull that thermo fan switch and test it.

 

Yeah what I think I'll do before I pull it out of the car is to let the engine warm up to where the fan should come on, pull the thermo fan plug and check for continuity on the posts of the switch, saves me from not having a running car if the new switch is actually bad.