Fan does'nt come on

[DONHOMER]

ENGINE fan does'nt come on when i turn on airconditioning but it does come on when engine temp gauge gets to 75% .is this normal?cheers

[304runner]

Brettjjj will be able to answer this one. My mate had almost the same issue but the other way around. The fan would only come on when the A/C was turned on. The sensor was rooted

[VrWagz1]

sounds like temp sensor rooted to me.

[Cheap6]

What car (presumably not the VH)?

If it's VS and without referring to a wiring diagram, I think it's more like a BCM side fault. The fan low speed is switched by the BCM but the high speed is switched by the PCM so would switch with high engine temp..

Both circuits run through a 5 pin relay under the bonnet. It's possible that that has failed or even been replaced with a 4 pin relay.

Yes, Brettjjj had an issue with the fan on his VS so if he hasn't replied yet, then that will be worth a search (about 6 months ago?).

If it's a VR, the fan should be on whenever the PCM gets a signal from the A/C circuit. If the A/C works (confirming that the signal for A/C request has been seen by the PCM) and the fan can be switched by the PCM at high temp. (confirming that the fan circuit works), then it's hard to see where any problem is (that's why I'm guessing it's a VS we're discussing).

[Brett_jjj]

My problem ended up being a faulty ECU not turning the cooling fan onto high speed.The low speed fan should come on with the A/C.Ive also had problems before with the low speed cooling fan relay,so Id first be swapping the low speed cooling fan relay over with another one the same, like the LP check relay.These relays are located under the bonnet in the fuse box.
If you carefully look at the middle pin on the relay,check if the plastic has melted slightly around the base of the middle pin,if it has,then the relay is stuffed and needs replacing.Ive come across this problem with these relays on a few VS's now that have had cooling fan trouble.

You can test the cooling fan to see if it works and switches between the two speeds by doing the following-

With the engine off,disconnect the ECU's coolant temp sensor wiring connector from the temp sensor on the front of the engine.The ECU temp sensor is the multi wired one.The single wire one is only for the temp gauge.
And once the wiring connector is removed from the temp sensor,start the engine.After around 12 seconds,the cooling fan should start to rotate at low speed,then after a further 6 seconds,the cooling fan should then switch to high speed.If it does this,the cooling fan and its systems are working ok.

[SWE11L]

You can test the cooling fan to see if it works and switches between the two speeds by doing the following-

With the engine off,disconnect the ECU's coolant temp sensor wiring connector from the temp sensor on the front of the engine.The ECU temp sensor is the multi wired one.The single wire one is only for the temp gauge.
And once the wiring connector is removed from the temp sensor,start the engine.After around 12 seconds,the cooling fan should start to rotate at low speed,then after a further 6 seconds,the cooling fan should then switch to high speed.If it does this,the cooling fan and its systems are working ok.

Hey Brett My fan doesn't come on either so I tried this and the fan comes. If my relay is ok too what do you think the problem is? Temp sensor stuffed? Cheers, Chris.

[Brett_jjj]

Hey Brett My fan doesn't come on either so I tried this and the fan comes. If my relay is ok too what do you think the problem is? Temp sensor stuffed? Cheers, Chris.

You say it came on,but did it switch to high speed from low speed after the 6 seconds?

[SWE11L]

You say it came on,but did it switch to high speed from low speed after the 6 seconds?

Yeah mate it did.

[Brett_jjj]

Yeah,Id replace the temp sensor then.Theres 2 on these cars,one for the temp gauge,its got a single wire,and the other multi wired one is the ECU one,this is the one you will need to replace..

[VS_Pete_1]

The shinny one on the right is the temp sensor.

[SWE11L]

Cheers Pete.

[DONHOMER]

Yes it is the VS V6 1995 model,thanks for all the replies.will try these suggestions.cheers

[Brett_jjj]

Let us know how you get on with it.Cheers.

[SWE11L]

Replaced my temp sensor this morning with one from the wreckers, fan comes on now when temp gauge hits halfway, awesome!

[DONHOMER]

OK. I'VE SOLVED MY ENGINE FAN NOT COMING ON UNTIL TILL 3/4 ON GAUGE PROBLEM. It was the low speed fan relay in the fuse box it has a green stripe on it and has 5 pins.The fan was not coming on at low speed or when I turned on the air conditioning .I replaced relay now fan comes on (low speed) when temp gauge is at 1/2 and also any time I turn on air conditioner.LOW SPEED IS PRETTY FAST HIGH SPEED IS EVEN FASTER.so it seems I only had high speed working all along.thanks for the help everyone especially Brett_jjj.cheers Donhomer

[304runner]

Cheers for posting your results.

Nothing worse then people making a help thread then fixing the issue and not posting the outcome. This thread will no doubt help many others who have the same issue....