Radiator fan driving me nuts!

Hi ladies and gents,

I have a 2001 mems 2 VVC F.

From purchase for the first few months I would often get home after a couple mile drive and find the radiator fan running needlessly.

I changed the brown CTS which was relatively new itself and sprayed the connector and fan relay socket with WD40 to ensure a clean connection. Seemed to do the trick.

The car runs at 1 dot below half way on the gauge and yesterday whilst the weather was hot we were stuck in traffic and without me realising the gauge has crept up to half way, and so still quite new to this car, I waited for the fan to engage but conscious of the temperature.

Slowly it got to near 1 dot above half and that was me convinced the fan wasn’t working as it should- heaters on full, much to the pleasure of my girlfriend.

The gauge quickly dropped down to below halfway again.

A little more driving and when pulling up I noticed the engine bay fan running and not the radiator fan despite agin the engine nearly definately being in need of cooling.

I wiggled the engine bay relay and then switched off.

An hour or 2 later continued our journey with more traffic and we had to make a toilet stop. Fan check= fan running happy days!!

Continued on for a few more miles on open road and park up- fan is still running and not switched off?

Ignition off and back on leaves it off.

Today I swapped the relay for the HRW one and ran the car up to halfway mark again hoping relay was at fault, but no fan kicking in. So cooled down with the heaters.

I then pulled off all the inspection hatch the removed the CTS wires- fan runs...

So I removed the CTS and checked the resistances cold and hot.

Cold 3.191 and hot 292, these are correct?

Can anyone help the apparently random workings of my fan?

Sorry it’s so long!

When you say you swapped the relays(hrw and fan), was this the relays in the under steering wheel fuse box?
There is another relay under the bonnet which switches the fan on and off. It's the yellow relay beside the under bonnet fuse box. It's possible this one is the issue.
By the way WD40 acts as an insulating coating when dry so is not good for electrical connections!
Get some electrical contact cleaner instead.:yesnod:
On Fs the two fans are controlled independently; the engine fan being controlled by the sensor above the coolant expansion tank. Disconnecting that sensor with the ignition on should start the fan.

Make sure both fans are rotating freely by hand. With the ignition off obviously!:woowoo: :doh: Youcan use your wd40 on the fan spindles if they are stiff.
Let us know what you find.

Yeah I swapped the HRW relay for the engine bay fan one as it is the same relay and no change.

The fans physically work ok as during the day the fan came on fine but it seems to be whatever that switches it on or off that’s faulty.

Either that or I’m chicken and don’t leave it long enough.

Should the temp needle move at all whilst the temp raises to fan cut in temperature?

Chicken!!!!

Once the engine gets up to temp. the gauge shouldn't move from its normal position before the fan(s) trigger.

Again if you get an obd2 dongle and the torque app, it will show you real time coolant temperatures.

Could I just add that my f runs just over 2 sectors under midway, always has from new. On idle tickover for any length of time, the needle will rise one sector above midway befor the fan kicks in which runs until the needle drops one sector below midway. Hope this makes sense.
The engine bay fans have only kicked in about 5 times in 47k miles, and only when the car has been in Spain in 28C plus, again when the car has been at idle. These fans continue to run when ignition is off until the engine bay has reached the correct temperature.

Thanks guys some good info coming in now.

I did wonder if I’m chicken. I’ve bought some electrical contact cleaner and will spray everything up today.

Which OBDII dongle would you recommend?

Workable with mems2 and iphone?

You've got problems both ways up there: to the best of my knowledge there are no simple plug in dongles, similar to those for OBD2 that accommodate first generation stuff, or more accurately Rovers take on it. Secondly the dongle I bought for ODB2 for Iphone didn't work first time around & the second was only a spasmodic worker. However others may have greater insight.

I’m sure I could source an old android from a friend or relative if need be.

Mems2 keeps rearing it’s ugly head in only ugly and annoying ways!

MEMS2j = Pscan & If I didn't have access to a Rovacom system I would have one in the workshop.

Pscan looks a cracking piece of kit!

Not sure I can shell out £154 right now sadly. Does anyone in the South East / London/ Kent have one they’d be willing to use on my car?

Several thoughts -

1) 2001 is late for a MEMS 2.0J, most VVC were MEMS3 by 2000, I am not saying it isn't but am suprised that it is.

2) If it is MEMS 2.0J then the brown CTS is correct, if it is MEMS 3 then that CTS should be black.

3) the dash gauge is feed by the blue CTS so is indipendant of the brown or black CTS.

4) If it is MEMS 2.0J then the most resonable scanner is a www.pscan.eu , if it is a MEMS 3 then it will be OBD2 and any OBD2 scanner will work.

5) As the dash and ECU CTS are independant it is possible that you have air in the system that is affecting the reaings of the two CTS.

James