VR6 fans

[Kevin Bacon 5]

Has anyone got a wiring diagram for the coolant system, in particular the path of the thin red/black wire that goes from the radiator bi-temp sender to the fan controller unit? I have an issue somewhere in the red/black circuit as speed 2 isn't coming on.

 

Since replacing the controller, the aux pump seems to run on for 10 minutes after the ignition is switched off, even if I just start the engine and switch it off again, is this normal?

 

Does anyone know what temps 1 and 2 should come on at?

 

Cheers

[ZippyVR6 0]

I think 1 comes on at 85. sorry but it all the help i can offer.

[Kevin Bacon 5]

Yeah that sounds about right, I've heard figures of 90 and 100 for the 1st and second speeds. Speed 3 comes on at 120 degrees, so you won't hear that one kick in often, if ever.

 

When it does, holy cow, it sucks litter off the pavement and the voltage guages drops to 11.5!! I suppose the 50 amp fuse for the 3rd speed hints at how current hungry it is!

 

Did a test yesterday...sat in traffic for 39 minutes and I let the coolant get to 100 degrees and oil 102, then manully flicked speed 3 on. It took 3 minutes to get the water down to 80 and the oil to 82! I reckon speed 3 would be better as speed 2.

[Supercharged 2]

Kev, the thermoswitch on the rad is only for the after run I think on a VR and is 2 speed, there is another one (midle one in the plastic housing) that controls the 3 speeds...

 

I take it the fan controller you got matched the one you took off??

[Kevin Bacon 5]

Steve, from what I can work out, the yellow (now black/blue) sender controls the after run. It seems to run a set 10 minute program after the ignition is off regardless of temp. If the coolant temp is high enough, speeds 1 and 2 will also run (ignition independant), which the rad sender controls.

 

The controller. Original part number was 357 919 506, dated 05/99 (so it's been replaced once already). Replacement is 3A0 919 506, dated 06/05 and it's exactly the same as the old one, but with some internal modifications according to VW head office. £82+VAT but Lindvale waive the VAT for me.

 

The problem I have is two fold. Firstly the rad switch isn't working as speed 1 isn't coming on at 90, and secondly, there is a break somewhere in the red/black wire off the rad sender which controls the 2nd speed......

[RW1 0]

Three speed VR6 fan works on four separate sensors. One is dual in the radiator for 95’C & 105’C – see detail below. The third stage is controlled from the outer position towards the battery in the thermostat housing. Sensor is black with green ring. It’s rated at 112’C. Run-on fan & auxiliary electric pump use the yellow temp sensor in the thermostat housing on the furthest offside position.

 

The cooling temps switching are ……

 

Stage 1 – ON 92’C – 97’C

OFF 84’C – 91’C

 

Stage 2 – ON 99’C – 105’C

OFF 91’C – 98’C

 

Stage 3 – Specified as 112’C

 

Fan Run-On – ON 101’C – 107’C

OFF 94’C – 100’C

 

-------------

(Corrado VR6 1992 - 1994 only)

 

As the stages 1 & 2 rad fan are coming on with the Fan Run-On circuit, the fan controller to fan motor wiring and fan are working and that part of the circuit can be assumed to OK.

 

The 1st stage not coming on may be the rad switch and you should check for 12 volts on the input side (red wire) and 12 volts on the output side (red/white stripe wire) when the switch is supposed to be on. The fan controller is not controlling this circuit, it’s a direct wired circuit to the fan motor. There is a splice in the red/white stripe wire so if the output from the rad stage 1 is switch on, it should appear at the fan controller pin 3 and the rad fan pin 2. Rad fan pin 2 is deriving it’s power from the rad thermo-switch. The connection into the fan controller is the same thickness but has no influence on the fan stage 1 working. The thickness of the wire at the fan controller is misleading as this is not the fan’s stage 1 derived 12 volts supply path.

 

I would doubt if the red/black stripe wire splice in the wire from the rad switch to fan controller has open circuited. I would look at the rad switch itself and both the rad switch connector and the fan controller plug connections for damage. The splice is inside the black taped loom. All it is doing is changing the wire size, 1995 Corrados use the thinner wire all the way from the fan, no splice.

 

The 3rd stage fan I doubt is rated for continuous running. It is drawing about 40 amps which the cabling is designed only to transfer power for short periods due to it getting warm. The fan motor is also likely to have a rating on it for continuous running due to internal heating. This stage cooling is on the car to cope with coming to a halt after a prolonged high speed drive (ie 120mph type pace on German Autobans on a hot summer’s day) where the engine has heat soaked and there is a need to dump heat rapidly for a few minutes until stage 2 fan can take over. In the 1992 – 94 Corrado’s the electrical circuit is definitely under rated for continuous running of the fan. Continuous usage could result in a loom fire in the back left side of the engine bay, ie a hot engine on a hot day.

 

A better method would be to fit an extra oil cooler and an additional switch/relay enabled fan in front of the radiator behind the grille. Or run the fan on stage 2 manually (Fan motor and wire ratings will handle this) by switching in 12 volts on the thin red/black stripe wire from the rad thermo-switch at the fan controller end on the nearside plug with the thin wires. This would be neutral to the rad therm-switch stage 2 kicking in and would therefore not create any backfeeds in the circuit.

 

Interestingly, although the same fan controller is used on a 1995 Corrado, it’s circuit has been revised and more fuses introduced or uprated. That’s a definite sign that the 1992 – 94 circuit has problems under extreme conditions specified for the car.

 

.

[ardandy 0]

Ok, being bamboozled by reading this and various other posts, can someone help me!

 

On MY VR, it appears that 'stage 1' doesn't kick in at all anymore, with the ignition on or off, but when it gets near 100c the fans do kick in, with a bit more va voom!! Any ideas?