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Cooling fan staying on?!!

R

roygarth

New member
The fan in front of car is staying on (for ever) when I leave car! Local spanner (no specialists nearby) suggested I find out likely problem before he starts investigating. For time being I'm disconnecting battery when I leave car (letting fan run for 10/15 mins to make sure engine cooled down before disconnecting.

Is there a new part I need or......?

Thanks in advance.
Piers
 
Piers,

I'm assuming you are talking about the oil cooler fan on the right side. If it's staying on with the ignition off the problem can only be a siezed relay. The relay contacts get welded together and won't let the relay release. The relay itself (in the front electrical panel) is identical to the one used for the rear blower whose relay lives in the electrical panel on the left side of the engine compartment. You can temporarily pinch the one from the rear and substitute for the one up front to diagnose the problem. If it works it's just a new relay needed.

Regards

Dave
 
Thanks Dave. I explained problem to JZ Machtech and they have sent me a relay. But there are 2 identical relays next to each other in front electrical box (the same as I have been sent) one labelled 'Front Blower' and the other 'Front Blower Oil Cooler'?? Which one is it? To confuse issue the problem has self corrected overnight ie Blower/Fan is turning off now with ignition!!
 
The oil cooler blower is relay R04. It is the relay at the end of the row.
The other relay is for the aircon condenser blower (this is R14).
My oil cooler wasn't coming on at all when I first got my c4. I found that someone had moved the relay across from R04 to R14. (I don't have aircon!)

HTH
 
The nature of the problem with the relay is that the current passing through the contacts can temporarily cause the contacts to weld together. When the relay is released (by the CCU) the contacts stay together - probably to release over time once the spring tension overcomes the weld strength. I wouldn't rely on it being a permanent fix though - changing the relay would be good I feel.

What Chris said about the two relays is correct - both are identical to the rear blower relay as I mentioned before.

I saw your similar question on Rennlist where somebody had suggested that the problem may be the ballast resistor. The ballast resistor is well known for be subjected to corrosion although it applies more to the aircon one on the left side because the battery vent tube exits directly over it. However, I couldn't see how a faulty resistor could give rise to a voltage able to keep the blower riunning!! Certainly, a faulty resistor might STOP the blower running but it ain't gonna MAKE it run.

Regards

Dave
 
All understood. But why have I got a relay in R14 when I don't have air-con?! In the relay box lid it lists R14 as 'front blower' - no mention of air con...
 
Because we all have climate control units regardless of air con, you'll also notice the air supply is always on, even with the dial on "0", it's the nature of the beast.

Front blowers are there to push air into the cabin, servo's dictate whether its cold or hot, and then mix according to the ccu requirements.

Kevin.

 
Try the heater tube temp sensor, that will make the blower fan for the oil cooler run, its designed to stop the car overheating when it's switched off, so in the event of a large heat soak, the temp realises its bad for the enginge, and switches the oil cooler fan on to stop damage occuring, a quick test of this working is to just pull the plug from the heater tube, if the fan fires up, the circuits and temp sensor ar ok.

Kevin
 
ORIGINAL: roygarth

All understood. But why have I got a relay in R14 when I don't have air-con?! In the relay box lid it lists R14 as 'front blower' - no mention of air con...
Click to expand...

Maybe some kind soul left you a spare!! If you have no condenser in the left front wing you don't need that relay. It's the same as the oil cooler and rear blower relays so it's handy to have a spare.

Regards

Dave
 
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