Problems with engine fan not working

[fnlow1]

Problems with engine fan not working [SOLVED]

Car in question is a '93 VP Calais V6.

From what I have read the engine fan should start when tempretures reach approximately half way up the gauge or whenever the A/C is turned on. The problem is my car is not always doing this. This morning the fan didn't appear to turn on at all and the car overheated after driving 10kms.

Fuses all appear okay. What else should I look at to try and diagnose this issue?

Engine fan relay? Temp sender? Crank angle sensor?

I am not exactly sure how to go about checking these things so any pointers would be great. Thanks.

Also car is not losing coolant, radiator hoses are new. Thermostat shouldn't be an issue. System has been bleed of all air. Water pump seems fine. So I am nearly certain the fan is causing my dramas.

 

[8rody]

The 10ks that you drove when it overheated, was that start stop city traffic with a average low speed?

 

[HoldrodeoLT]

Is your radiator heating up? touch the top hose, is it still cold? Are you 100% sure it isnt the thermostat?

 

[fnlow1]

The 10ks that you drove when it overheated, was that start stop city traffic with a average low speed?

9kms was main road light traffic. Last km i caught a few sets of red lights.

Is your radiator heating up? touch the top hose, is it still cold? Are you 100% sure it isnt the thermostat?

Boils into the overflow. Top hose is hot, radiator cap is hot, bottom hose is hot- everything seems pretty damn hot. It's not the thermostat.

99.999% sure the fan is playing up.

 

[Cheap6]

There's a bit of info. on how the engine cooling fan is switched in the "how to" section, on "how to add an auxilliary fan switch".

The fan is switched by the ECM.

The fan should turn on with the A/C at low speed so if that's not happening there's a fault in the fan switching circuit somewhere.

Ideally you would have a voltmeter to be able to check the ECM terminal that earths the relay - this is what the blue/white wire connects too, voltage potential between that and earth will be present only while the fan relay is not being switched by the ECM. That will tell you if the ECM is trying to switch the relay and compare that to fan operation.

It's possible that the ECM 'thinks' that the coolant temp. does not warrant turning the fan on - it should still work with the A/C on. This might be the coolant temp. sensor - the ECM uses a different sensor to the gauge - the wiring between the sensor and the ECM, the wiring between the relay and the ECM or fan, or the ECM being faulty.

Basic checks in the absence of test equipment:

Swap the fan relay (under the bonnet) with, say, the horn relay.

Check/swap the fan fusible link (in front of the relays).

Check the fan works by separating the fan motor terminal connector and applying external (direct to battery) earth and power wires.

To check the wiring from the relay to the fan, connect the fan relay terminals with a wire between the terminals in the car that connect to pins 87 and 30 on the fan relay - relay removed. The fan should then work. Pins are labelled on the relay.

If the fan is being switched by the ECM, you should be able to hear/feel the relay click as it switches i.e. have someone switch the A/C on and off while listening and/or touching the fan relay.

 

[fnlow1]

Cheap6- I really appreciate you taking the time to write that post- thanks mate.

Last night I connected the fan relay terminals as you have suggested. Going for a 10km drive the gauge didn't get past the first mark. In my mind this confirms two things- firstly, the fan motor and wiring are working and secondly, the overheating issue is indeed related to the fan not operating as it was designed to.

I will work through as much of that list as I can over the weekend and then if I still can't solve it I may have to give it to an auto eleccy.

 

[Cheap6]

No problem. One more thing you might like to check is the interior fan fuse, in the fuse block under the instrument cluster, as that provides the power to the switching side (pins 85 and 86) of the cooling fan relay.

 

[8rody]

I've the same problem, (though I have a few more, leaking timing cover, etc) so i'm not the best example, but indeed my thermal fan does not kick on at all.

I thought that the coolant temp sensor may be dodgy, but my understanding of EFI is that if that was so I would be getting horrendous fuel economy. However I am not.

In my car a VN S1, the area behind the fuse on the fuse block (in cabin) for the fan/cooling/aircon was melted, but the fuse was fine.
I suspect dodgy electrics somewhere on mine. I've wired the relay for the thermal fan permanently via a toggle switch, a little differently than the writeup - because I did not want to hack into my engine harness.

 

[codie101]

ive got the same problem wiv my vr commodore ,i removed the bellmouth earlyer that day and reset the computer now its over heating nd cooling fan not working any ideas thank

 

[fnlow1]

Thought I might update this to let people know I got my issues sorted over Christmas. Firstly I cleaned the relay contacts again and since then had no dramas with the fan cutting in and out. However, it was still getting hot at times- long story short, I found a split in the end tank so ended up replacing the radiator, also did heater tap etc while i was there, and ever since she has behaved beautifully no matter what the temp- even 40C+ days over summer.