Radiator fan not coming on

[rhys.l]

My dc2r is having a problem where the radiator fan will not come on. Doesn't matter how long I let it idle, or how I drive the car, the fan will not come on.

I'm thinking an issue with the engine coolant temperature sensor...what do you guys think? How can I test this is the issue before I buy one? I was thinking about wiring the fan straight to something else to make sure it is not dead, but I'm not sure what is pos and neg on the fan connector. Thanks for any help

[Benson]

Disconnet the fan switch plug. Turn the car on red's and bridge the wire on the fan switch plug

If the fan doesnt turn it, fan needs replacing and if the fan turns on, fan switch needs replacing

[rhys.l]

Thanks. Which is the fan switch plug? Is this the one that sits on the firewall side of the thermostat housing on a B18? What do you mean by bridging the wire on the plug? Do you mean short it?

[rhys.l]

This is the sensor I was referring to:

http://www.ozhonda.com/forum/attachment.php?attachmentid=18718&d=1306221245

[j0nn0]

If your car is not over heating.... ? well?

Its working. >_>?

[trism]

Exactly. If the fan isn't coming on, but the temp is going above half, it obviously isn't getting hot enough.

Sent from my custard cannon like Peter North.

[Vtakk]

I have the same problem with my EJ8 civic... but my engine not seem to overheat? everythings fine..thats odd lol even if i hit vtec

[Benson]

This is the sensor I was referring to:

http://www.ozhonda.com/forum/attachment.php?attachmentid=18718&d=1306221245

Unclip that plug and use a wire or paper clip to bridge the wire (i.e short the wires)

[rhys.l]

Exactly. If the fan isn't coming on, but the temp is going above half, it obviously isn't getting hot enough.

Sent from my custard cannon like Peter North.

Yeah as with Vtakk, despite the fans refusing to come on, the car will not go above its normal operating temp (just under halfway) according to the temp guage. I don't understand it at all. If the car is not overheating should I just not worry about it? Can I definitely trust the temp guage?

Cheers Benson, will give it a go

[j0nn0]

If its not over heating then dont worry about it. If you dont trust it.. get it looked at..

All he will probably do is sit in the car and pretended to be a f1 driver and floor it. Then it will go two ways from here

1. Fan will come on and you will be like :) :)
or
2. Smoke, massive explosion, earthquake, pissing in pants, :( :(

[rhys.l]

Shorted the plug and the radiator fan came on fine.

It's hard not to worry about it, that's all. All other cars I have owned have to turn on their radiator fans to maintain engine temp. It doesn't make sense this car doesn't need to, maybe it has some sort of super dooper coolant? Last thing I want is my car to blow up in a traffic jam...I might get someone to have a quick look.

I've found there are 3 parts that control the fan coming on, and the reading on the temp guage:

- engine coolant temp switch (on the thermo housing, tells fan to come on)
- engine coolant temp sensor (under distributor, measures temp coolant?)
- engine coolant temp guage sending unit (under distributor, relays message to temp guage)

Wonder if I should just replace them all...

[j0nn0]

Probably leave it alone, it works!

Same thing happpened with my car man.. I was 100% it didnt work.. since it never came on after long drives, hot days etc.

It would only come on when needed.. and apparently my car never needs it xD

But I did manage to make it come on.

Your choice man.

[trism]

My commodore, the only time the fan comes on is sitting in traffic on a hot day.

But if you're worried about it, replcae the thermostat.

Sent from my custard cannon like Peter North.

[Bludger]

Shorted the plug and the radiator fan came on fine.

It's hard not to worry about it, that's all. All other cars I have owned have to turn on their radiator fans to maintain engine temp. It doesn't make sense this car doesn't need to, maybe it has some sort of super dooper coolant? Last thing I want is my car to blow up in a traffic jam...I might get someone to have a quick look.

I've found there are 3 parts that control the fan coming on, and the reading on the temp guage:

- engine coolant temp switch (on the thermo housing, tells fan to come on)
- engine coolant temp sensor (under distributor, measures temp coolant?)
- engine coolant temp guage sending unit (under distributor, relays message to temp guage)

Wonder if I should just replace them all...
chage the fan switch where that plug was plugged into.

guarantee problem solved. you know the fan works.

[rhys.l]

Yeah you guys were right, thankyou!

After it was warmed up, I idled the car at 3000rpm for a good 5 minutes. And sure enough, for a brief 3 seconds or so, the radiator fan came on. There obviously needs to be some pretty extreme conditions before it is triggered. Very happy anyway :)

[Vtakk]

Probably leave it alone, it works!

Same thing happpened with my car man.. I was 100% it didnt work.. since it never came on after long drives, hot days etc.

It would only come on when needed.. and apparently my car never needs it xD

But I did manage to make it come on.

Your choice man.

I remembered my old Honda accord's fan wont turn on unless it needs to. If the fans left on..it will make alot of noise when idle and driving. As long the fans work and spins when need to its fine... if it doesnt turn on at all then yeh there mite be a problem lol
as long you got a super duper awesome radiator coolant and its still fresh and green then your the awesome

[Bludger]

Yeah you guys were right, thankyou!

After it was warmed up, I idled the car at 3000rpm for a good 5 minutes. And sure enough, for a brief 3 seconds or so, the radiator fan came on. There obviously needs to be some pretty extreme conditions before it is triggered. Very happy anyway :)
3 seconds sound a bit short.

I know that DC2 with after-market full size aluminium radiator, it NEVER gets to operating temperature.
Have to sit there revving for nearly 10 minutes before fan comes on.

Just be aware that your fan came on when you shorted the wires, but make sure your fan switch is operating correctly. like I said, 3 seconds is short.

Cooled coolant should take nearly 10 seconds more or less(most likely more) to circulate from the radiator, throughout the motor then to the thermostat housing where the fan switch is.

[rhys.l]

Yeah when you put it that way it seems as if there could still be a problem.

Just before the fan came on, we put aimed a heat gun at the upper radiator hose and it read 82C. According to the guy next to me, that was barely hot enough even though at that instant the fan did decide to come on. I think at this stage I'll just trust my engine temp guage and just keep an eye out for any signs of overheating.

BTW I was given and am running blue OEM coolant. Vtakk mentioned green above...is blue the right stuff for my car?

[Vtakk]

hmmm im not sure. But i know that most radiator coolants are green or greenish colour

[rhys.l]

Apparently I have the right stuff, OEM is just blue