JasonHi

anyone know what other causes why the cooling fan wont turn on? ever since we swapped the motor (d16z6) cooling fan isnt working right. right now its hotwired to a switch. Relay, fuses both under dash and under hood, and the fan switch by the thermostat are good. switched the thermoswitch twice, one was from autozone, the other from honda, still not working. when i jumped the wire that connects to the thermoswitch, the fan turns on though.

civic_driver

If you jumped the thermo switch connector and the radiator came on then that means your fan is working but you're not making the engine hot enough to turn on the fan.

On my 99 civic I have to hold the gas for about 3-5 minutes from a cold start at around 3K RPM (in neutral or park) in order for the fan to come on. It is probably the same for your civic.

JasonHi

it does get hot enough. the temp guage goes pass the middle and still the fan wont turn on.

civic_driver

Are you using a thermo switch for a d16z6 or for your old motor? Make sure you're using a switch for the new motor.

Also, the temperature gauge sending unit might be bad on your d16z6 and that's why it might show the arrow is getting past the middle while the engine is not overheating at all thus the thermo switch is not turning on.

Also, measure the voltage you're getting at the radiator connector when you jump the thermo switch connector. I think it should be 12.5V with the car off and 14.1 with the car running.

Falqon

Jump the relay as well just to make sure.

Former User

Is the fan switch connector damaged and not making contact with the fan switch terminals?

civic_driver

Oh yeah, Ron is right, didn't think of that.

JasonHi

yes i tried the one that came from my old motor, then the one that come on the motor that was swapped, then the one from autozone, then the one from honda. still no luck.

just tried my friends relay off his car and still the fan wont turn on.

yup. double checked it and the plug clips on perfect onto the thermo switch. the female part of the plug looks okay too.


this just doesnt make any sense. Thanks for all the help guys.

Former User

Your facts:

1) Fan runs with fan switch connector jumped.

2) Fan switch is fine.

Logical reasoning:
Logic dictates that the problem lies somewhere between the switch and its connector.

JasonHi

yea it just doesn't make sense. I'll put the genuine honda thermo switch back tomorrow and make sure the plug and thermo switch is snugged on tight because its too cold and dark right now LOL.

BTW i dont think the temp guage sending unit is bad because it takes about 10-15min sitting in idle to get it pass the middle.

Oh yea also it cant be the thermostat because i just replaced it with genuine honda thermostat too.

turbohatch96y7

iTrader: (15)

hey did u bleed all the air out of your coolant system cause if u didnt u wasted alot of time and money..
this should be your bible by now https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/faqs-frequently-asked-tech-questions-1998336/

but to get u ahead remove your radiator cap and let the car warm up then put the heater on and set it to your feet let your car run till the fan turns on adding water to your radiator as it comes out.. its also faster to jack your car up so it travels to the radiator faster...

JasonHi

yup i did that twice today LOL. but instead of jacking up the car, i just parked on my super steep drive way.

btw thanks for the link!

turbohatch96y7

iTrader: (15)

did u do it till your fan turned on it usually take about 10-15 minutes

JasonHi

thats the point of this thread LOL. the fan doesnt turn on. its wired to a switch at the moment. but i filled it all the way up and let the car run till no bubbles were comming out while heater was on full blast then i let is sit for a while and re-filled it again. the car doesnt overheat unless i turn the fan on.

JasonHi

well, i just checked the plug and thermo switch and it's seated on there properly and has good good contact. i'm stumped. anyone else have any ideas?

B16AJDM

It has to be the sending unit that's on the outside of the thermostat housing. I just had a post up last weekend about this same exact thing man and that's what it ended up being.

civic_driver

Best way to figure out if the connector is making a good connection with the switch is once you warm up the car, measure voltage drop across the connector/switch. If the voltage drop is small, less than say 0.5V, then it's making good contact; otherwise you will have to get a new connector soldered in.

It's gotta be the connector at the switch or the switch itself and since you have ruled out the switch, it should be the connector.

civic_driver

Btw, that's the ECT/fan switch you're talking about. The sending unit is screwed in the head under the distributor and has one wire.

JasonHi

no the sending unit doesn't have anything to do with activating the fan. It's for the temp guage.

JasonHi

Are you saying to measure the voltage with the plug plugged onto the sensor or off?

Deemy2287

fuse, realy, r fan not gud

civic_driver

With the plug connected to the switch. Simply insert two sharp probes into the wires and measure the voltage across the two points. The first point should be on the first wire and the second point should be on the second wire of the fan switch connector. If the voltage is less than 0.5V then that's not the problem, otherwise you need a new connector. Remember you have to warm up the car enough to make sure that the fan switch engages in order to measure the voltage drop.

Check out the diagram below:

JasonHi

okay thanks man!!! and what should the voltage reading be when the car is still cool? 0?

civic_driver

Yeah, when it's cool it should be 0. You don't even have to measure it when it's cool. The important voltage drop is when the switch turns on. Then you will know whether the connector makes a good contact with the switch.

dmingis

What was the resolution on this?