That Cooling Fan Problem, again!
 

I have a 1.8T and firstly I will state that I have followed the advice on here of trying to find the answer to this, so here we go.

The high speed fan comes on pretty soon after starting, and most times when I stop and switch off the engine, that high speed fan runs on for about thirty seconds , though often it will start again, once I've switched off th ignition, and even been operating when I've returned to the car.

I have tried the sequence of running on idle, set the Econ and then demist and the low speed fan operates, which I believe is normal.

Having had the bumper off to try to find the lighting wiring fault I took the opportunity to check and found that I have a silver, original resistor. I cannot see where there is any other relay around the fan.

Polite suggestions are requested, the rude ones we'll get to later.

It's unusual to hear of an original silver resistor lasting so long. Are you confident of the Demist Test result? The low speed should run continuously until you turn Demist off. A failed resistor causes the high speed to trip on after the aircon's been running a short while. This will then trip off and on every 15-30 seconds or so. The Demist Test should be run for a couple of minutes or more if you're unsure whether it's the low speed or high speed that's operating. The 'low' speed is pretty noisy.

High speed fan operation with no obvious temperature requirement can occur if the temperature sensor signal is missing or intermittant. One possibility therefore, is a bad connector or wiring to the temperature sensor. The sensor is screwed into the head on the RHS as viewed, just below the main coolant outlet. That's my suggested first check.


https://www.mediafire.com/convkey/cf...kw4bb6r56g.jpg
If the sensor and wiring is OK, then a fan running on after ignition off is usually a sign of an overheated engine. The 1.8 system can do so for up to five minutes. If it runs on longer than that, I'd suggest checking/cleaning the two connector plugs mounted on the nearside wheel arch (bumper off) also check the relays. Are you certain that this fan behaviour isn't due to a very hot engine? If there's any doubt, the best way to check is the Trip Screen Diagnostic routine which tells you the exact temperature in degrees Centigrade (the gauge on the dash is relatively meaningless). Here's a link to the Diagnostic routine: https://www.the75andztclub.co.uk/for...t=Running+temp

Another thing to check is the fan control box which is attached to the rear side of the fan framework. This contains the fan switching relays for high and low speed. Be aware that the fan system is on a permanent live feed. Earthing certain parts of the sytem may inadvertently cause the fan to run. To ensure safety when working on the fan system, remove the 80amp fusible link in the under bonnet fuse box.

You really ought to upgrade the silver resistor while the bumper's off. You can get the recommended 'gold' type from electronics outlets like Farnell, from forum traders and from ebay.

TC

Need some help. Yesterday went to visit my Dad in Burslem hospital after he had a stroke. Traffic jams everywhere, Moonstone V6 overheated and spat out 2 pints of coolant. 3 miles later, still slow moving, did it again. Let car cool down in Haywood hospital car park, re- filled, another 2 pints, and drove back home, over 70 miles constantly moving and not lost a drop since! Checked the fan on demist and it has stopped working. This is a Y reg 2001 V6, what fan do I need to fix it, where do I get from. Any advice appreciated, thanks.

As you have a Y reg - i think you will have a 3 speed fan - when they fail it is a question of replacing the bushes - search on e bay they are inexpensive -£20.00ish.

If you have a 2 speed fan then it is usually failure of the resistor - go to the front of the car -look RHS through the grill - can you see a resistor - silver in colour 4-5 cm's long - if so you have a 2 speed fan you will see a resistor - if so the resistor needs replacing with a gold coloured upgrade - £15.:}

Thanks for that, could not see a resistor, just looks like 3 wires going to the motor, will try to find brushes then.

Look through the front grill and see if there's a long thin aluminium 'block' located in the 2 o'clock position behind the fan blades. You may need a torch and a thin stickor a cane to move the blades. If you see this, then you have a 2-speed fan and this block is the resistor that needs swapping out. You can get the uprated gold ones from electronics outlets like Farnell, from forum traders and from eBay. If there's no resistor as described above, you have the earlier 3-speed system. Fixing this is more complicated and with luck may be fixed by renewing the motor brushes. If the armature of the motor is in bad shape (it depends how lucky/unlucky you are), the whole shebang is swapped out.It's best to repalce the fan system with a later 2-speed/resistor controlled type. This is a plug'n'play exchange.

There are loads of threads and a HowTo or two on swapping the resistor. It requires the front bumper off and a bit of drilling/crimping/soldering/etc. depending on what you buy. Some kits have ready to fit resistors some need a bit of work soldering and drilling and others even more work. It depends on your DIY ability/available time/wallet/just like everything else.

EDIT: Oh you posted just before me. You need the good spec brushes if you want a lasting result. There's a link somewhere to an engineering carbon company that custom manufactures 75/ZT brushes of the proper stuff.

Hang on, just found it. Scroll down left hand side to find them: https://www.ecp.co.uk/

Here's Arctic's HowTo on YouTube: https://www.youtube.com/watch?v=ls1B...ature=youtu.be

TC

My apologies to T-Cut for not replying, nor even acknowledging your contribution.

I'll come back to this in the morning.

Not eBay, ECP!
 

Martin; to avoid brushes of unknown manufacture which don't last, it's best to recommend that members buy directly from Engineering Carbon Products Ltd. who designed and produce their brushes from a sample sent to them by me. T-Cut has provided the web address above.

Simon

Ordered as suggested.
Thanks

Hi Martin.
Are you and Steve going to have a go at repairing the fan your selves, remember from your visits to the Nano it is bumper off, slam panel off, then remove the fan and it's cowling with out disturbing the A/C gas.

Also I am only at the end of the phone which I think you have already cheers Arctic.

PS I presume these are the brushes you have ordered.
https://www.ecp.co.uk/rover75-carbon-brushes.php