Overheating - rad fan not working

[Soot]

New member here - *waves* I was advised to come here by the friendly folks on the Parkers forums.

Car: Lovely red 1999 Clio 1.6 RXE (Automatic)
I've had it since January 2006 & driven 4,000 miles since then (odometre currently at 58,000 miles)

It passed MOT in July and then had a Renault Minute service in September.

I overheated once on the M25 in September (before the service) - no cooling water (although turned out not be a leak, just a stupid owner/driver: me) - and they diagnosed "overheating" as a problem during the service. I stupidly paid for Renault diagnostic, whereupon they told me the Head Gasket was ok and they'd need to run further tests (thanks guys, that's about the one thing I could have checked myself), but basically the radiator fan wasn't kicking in.

True enough, October rush hours started and, yes, it overheats very quickly in traffic. And of course I now feel guilty that I broke something when it overheated on the M25 that time.

Took it to another garage (who were highly recommended by several people). They changed some thermostat thing that's supposed to sense when the fan should kick in - nothing changed. They've now had the car back for three days and it looks like the problem is electrical. Something to do with the ECU and/or cable harness? I'm a little bit confused and was hoping this might sound familiar to someone, so as to explain it to me in dummy!speak.They also said they'd be giving me repair quotes on Monday and warned that it would be "very expensive" and there would probably be a £300 difference between fixing it with new or second hand parts .... Perhaps I could have some help with the quotes on Monday? :dapprove:

I know this is vague, but I'm hoping it might ring a bell in someone's memory ... perhaps a smiliar experience? I also have **no** idea what to expect cost-wise. "Very expensive" to them might be very different than "very expensive" to me? I don't know how much the car is worth to me ...

/end rant and nervous breakdown!

 

[Soot]

Update

[FONT=Arial, Helvetica][FONT=Arial, Helvetica]Sadly, the garage has confirmed that the harness and ecu are somehow damaged .. They have said it will cost around £800 to fix all this, but don't think it's worth it given that I got the car for 3,200 in January. So they're going to add a flick switch so I can switch on the fan manually when I hit traffic etc - for less than £150. I realise that's probably overcharged, but I can't do it myself and it's a lot less than £800! He said I could think about changing the harness and ecu when I had the money.

So my new questions:
a) does this sound like a good idea if only for the short term?
b) could the damaged harness and ecu affect other parts of the system or should it be safe to drive with it as is for a while (garage said it should be ok as nothing else seems to be having problems right now)

... thanks!
[/FONT][/FONT]

 

[Rob Clark]

depends. general system works along the lines of

coolant sensor (+others?) gives feedback to ecu about temp
ecu provides dash with indication of temp
ecu switches rad fan on when indicated temp via sensor passes a certain threshold.
thermostat is passive component which redirects flow of water into radiator when it warms up and forces a change in direction which your saying has been changed (easy enuf to test)

Now, assuming the ecu is receiving a signal from the coolant temp sensor (shud be able to check via renault computer / obd) it should be then switching the fan on at a certain point.

Also, does dash give indication that temp it going too high ?

Should be possible to check the ecu if pinouts are available to see if the fan on pin goes high at a certain point and to see what input its getting from the sensor.

re wiring loom, unless the connector is heavily corroded or wires damaged then is strange and possibly very awkward to trace

 

[AlanusMaximus]

Hi, I had the exact same problem on my mum's 2004 1.4 auto... Is yours an auto too by any chance? I'm prob 6 months late bud, but I am a mechanic and when this fault occurred om my mum's car I told her exactly what the garage told you... £800 for new loom and/or ECU... but when I took out the battery tray and checked the bottom of the loom... I saw an earth wire for the fan which had broken loose! You can see it's a common fault as it is a really crap design... It cost me £1.29 for the loop connector. I crimped the wire into the loop, bolted it to the gearbox, and problem solved!!
I only hope the garage was honest enough to let you know.....

 

[bmh.01]

Valid point but 2006?