Hi, does anybody have or can a link be supplied for a schematic wiring diagram for the cooling fans and control relays etc on a 53 plate VRS please?.

I have a Haynes manual, but unbelieveably, it makes no mention of the fan system or aircon at all - so according to them, they dont exist.

Any help would be much appreciated.

Regards

Phil.

The cooling fans are controlled by the fan controller. There are different wiring schemes/components for Climatronic/Non-Climatronic, etc.

What problem do you have?

I have a climatronic vrs, that has a fan fault - fans do not seem to come on at all when engine up to temp, although they work when A/C is switched on. I just wanted to diagnose the system to perhaps confirm a faulty rad fan switch, or to check if the fault was more in depth. Have code read the system and it is completely clear.

Thanks for the reply.

What year is the car?

53 plate/04

First check both fuses are intact. The fan control unit is fed by two of the fuses on top of the battery - the third of the bolt down fuse links and the green fuse nearest to them.

KEEP YOUR FINGERS AWAY FROM THE FANS - THEY CAN START WITH THE IGNITION OFF!

Next, remove the connector from the thermo switch.

Short pins 2/1 to activate low speed fan.

Short pins 2/3 to activate high speed fan.

If both speeds work OK, then all the wiring and the fan controller are OK.

Cheers rwbaldwin, is the connector block marked with the pin code numbers or do I need to source what colour wires go to these pins?.

Very much obliged for sharing the info, thank you  

The common supply is on pin 2 and is solid red. The cables to pins 1 and 3 are red with a stripe. IIRC, the stripe is white for low speed and yellow for high speed. When you do the short, make sure you have a chunky bit of wire.

Would I then be correct in assuming that subject to the system tests being ok, that this would then confirm the rad switch?. Many thanks.

You already know the fans run at stage 1 (low speed) because they come on with the a/c. If the fans run at both speeds when you short the thermo switch contacts, then you know that the fan controller is OK, fans are OK, power is OK, etc.

Assuming you have normal flow/coolant level in the cooling system, then this would confirm a faulty thermo switch. If your water pump is failing or the thermostat is sticking closed, you may overheat without the fans coming on.

The coolant system is under pressure, so you can get temperatures over 110°C. The test temperatures for the thermo switch are as follows...

Stage 1. on: 92-97°C, off: 84-91°C

Stage 2. on: 99-105°C, off: 91-98°C

As you can see, if you put the thermo switch in boiling water, stage 1 should switch on and stage 2 MAY switch on. This makes the thermo switch difficult to test.

Really Daft question, is your car actually overheating? All you said is it gets up to temp? Have you tried reading the engine temp using vcds? You might not have a problem and just worrying over nothing

Hopefully this should answer both queries from you guys, the car starts fine from cold, runs up to tempertaure within a mile to a stable 90 degrees. It stays at this temperature uphills, at speed, and driving normally.

However, if I sit in bumper to bumper traffic for about 15 minutes, the temperature slowly creeps up as you would expect it to do. I let it rise to just over 95 degrees, waiting for the fans to run, but nothing happened.

At this point I promptly bottled it and switched the A/C to auto (I normally run in Econ mode at this time of year) which brought the temperature rapidly back down to 90 degrees within seconds. The car has had a new cambelt, waterpump, auxilliary belt and tensioner fitted by a Skoda main agent about 2 months ago when I first got the car. It has also had a green CTS fitted by the previous owner in October last year according to the substantial documented service history with the car. The radiator is getting warm with no evident cold spots.

I have checked that both fans are physically able to turn by turning the A/C on when I got home. I am reasonably certain it is a fan fault because as soon as the car is out of traffic for a minute or so, I can turn the A/C back to Econ and all is fine again at 90 degrees.

Many thanks to all that have had input on this, especially rwbaldwin.

It's good news that switching on the a/c brings the temp down. It shows you have proper coolant flow.

My guess is that the Stage 2 fans would come on if you waited longer and it is the Stage 1 part of the thermo switch that is faulty.

Hopefully this should answer both queries from you guys, the car starts fine from cold, runs up to tempertaure within a mile to a stable 90 degrees. It stays at this temperature uphills, at speed, and driving normally.

However, if I sit in bumper to bumper traffic for about 15 minutes, the temperature slowly creeps up as you would expect it to do. I let it rise to just over 95 degrees, waiting for the fans to run, but nothing happened.

At this point I promptly bottled it and switched the A/C to auto (I normally run in Econ mode at this time of year) which brought the temperature rapidly back down to 90 degrees within seconds. The car has had a new cambelt, waterpump, auxilliary belt and tensioner fitted by a Skoda main agent about 2 months ago when I first got the car. It has also had a green CTS fitted by the previous owner in October last year according to the substantial documented service history with the car. The radiator is getting warm with no evident cold spots.

I have checked that both fans are physically able to turn by turning the A/C on when I got home. I am reasonably certain it is a fan fault because as soon as the car is out of traffic for a minute or so, I can turn the A/C back to Econ and all is fine again at 90 degrees.

Many thanks to all that have had input on this, especially rwbaldwin.

Did you solve your problem? I have exactly the same problem.....