VR6 fans not coming on

[eugopnosaj 0]

Hey guys, as the title says, the fans aren't coming on. This is at neither the 1st or 2nd stages (and should be third but that's a different question!)

 

I won't bore you with how I know, subject to say the warning light came on, filled it, came on again, filled it, did a test in a car park, 15 minutes to 120 degrees, warning light on, fans aren't turning on. I check the fuses and the 5amp is blown on the controller and the 10 amp after run is also blown. Swap these out and let it cool down for a bit, letting it heat back up again and still nothing, checking the fuses again and they're fine.

 

Both top and bottom pipes are hot but this doesn't rule out a blocked/broken thermostat. Failing that it is an electric problem as 2 fuses were blown?

 

The question regarding the 3rd stage is I have the black 3rd connector in the housing but there's no cable attached to it? It hasn't got AC (although I do plan on fitting the brown 4 pin sensor and wiring this in as I have climatronic fitted). It is also a later '94 car and according to the definitive guide all later cars were 3 stage?

 

Any help would be much appreciated, currently 60 miles from home and will probably have to get it recovered! As although there is a nice 70mph motorway to keep things cool getting there proved too hot in the first place! (well, coming off the motorway anyways...)

 

Thankfully the oil doesn't appear milky so looks like I've dodged a bullet there, I cannot see any leaking pipes or anything else untoward immediately.

[Rado87 10]

Ive recently had trouble with this and it was fuse number 19, 30A. Also, relating to the black sensor on the stat housing, mine doesn't seem to do anything either. Thinking maybe a blank used only on certain models?? Another thought, does your auxiliary water pump work ok?

[eugopnosaj 0]

I've checked fuse 19 and it's fine, that and the 20A one on the controller were both good whilst the others had blown.

 

There is power at the 'big fixed fuse' (the one that is screwed on) so it's getting power.

 

I imagine the aux pump works, wouldn't know though to be honest, but surely the standard pump will drive enough fluid through anyway especially as the whole system is hot and not just 1 half of the engine.

 

I'm going to take the black sensor out and swap it for the brown 4 pin for A/C anyway so that doesn't matter but yeah, possibly just used to fill the spot?

[Rado87 10]

I suppose you could try bridging the terminals out in the yellow plug not he stat housing and the wiring to the temp sensor on the rad to see if the fans do actually work? Thats one of the things I did with reference to the definitive cooling guide. If not, might need new fans. When you turn your ignition on you should be able to hear the aux fan whirring away, plus Im pretty sure that if it isn't working it can cause over heating issues.

[eugopnosaj 0]

Do you mean aux pump? On a clear run on a motorway it's fine, as it should be but obviously that's no indication of anything working properly.

 

I'll short the terminals tomorrow to test, already read a bit on the guide for reference so I'll use it as a step by step to rule out potential issues.

 

Got it recovered home, didn't want to risk of sitting in traffic and it fully overheating, the break down man reckoned the controller although he had no way of checking anything apart from seeing that there was 12v on a sensor and the main fuse for the controller so I'll take that with a pinch of salt :lol:

[Rado87 10]

I did mean pump! Lol! Hope you get it sorted either way mate, can't have these beasts getting too hot!! 😜

[eugopnosaj 0]

Haha yeah me too, plus I'm car less at the moment too!

[Rado87 10]

Nightmare! Let us know what it turns out to be if you can.

[Jim 2]

Awesome diagnostic information and overall setup of the cooling system on the VR is available here:

 

https://sites.google.com/site/stoyneff/miscellaneous/the-vr6-cooling-system

 

I'd certainly start by double checking the fan power connector is in place correctly (I've known them to break / drop off) then test bridging the temperature connector pins and seeing if the fan comes on. That ensures the fan itself is working, and that the problem may lay upstream - such as the yellow temperature connector, or the rad fan switch itself.

[eugopnosaj 0]

Thanks Jim I'll have a butchers. I've been meaning to look into my system anyway so I can wire in the aircon controls for my climatronic so seems like this is the opportune moment to do so!

[fla 9]

First bridge the rad temp sender next to the battery. Fans should come on even without the ignition on. If ok move to the wiring and check that to the controller looking for obvious breaks or loose wiring.

[eugopnosaj 0]

Bridged the connections on the rad switch and the fans don't come on, connecting the red to the red/white cable the aux water pump comes on though? Red/black does nothing.

 

Does this mean the controller is probably shot?

 

Also should I have a run on relay?

[eugopnosaj 0]

Any ideas?

[It's not a Scirocco 10]

I think your problem is the fan. Bridging the rad temp sender is the test for this. If the aux pump came on then this shows the stage two circuit is functioning correctly ( except your fans).

I believe the run on is controlled by the fan controller although there is a mythical relay no.14

[eugopnosaj 0]

I thought it was relay number 15? I too thought that since the aux is coming on that the wiring is probably fine and the controller is happy enough to turn this on.

 

Reading a bit more the low speed isn't even controlled by the module so it should have come on when I'd bridged it

 

I'm going to try and force the fans to run later today, there are 4 connections, red/white is speed 1 direct from the rad switch and fuse 19, (30A hot at all times) so should have turned on when it was bridged, red/black is speed 2 from the controller and the red/green is full speed again from the controller, although as my system is only set up for 2 stage at the moment possibly 1 of these isn't utilized?

 

I can use these connections to test the output on the controller whilst the engine is running and check for 12v and likewise feed power directly to each connection and see if it spins?

[fla 9]

Try power directly to the fans to check they're ok. The sensor connects directly to the fans so either its goosed or the fans are.

[eugopnosaj 0]

Put power straight to the fans via 12v to all three connections; red/white, red/black and red/green and nothing.

 

Started the car up and ran it till it got warm to the point when power should be fed to the fans and i got power to red/white, eventually got power to red/black but then it turned off? But never got power to red/green? The system got up to about 110 before I turned it off.

 

I guess the fans are shot, but also shouldn't there be constant power to red/black once it turns on and what about red/green (big fat cable)?

 

At no point did I hear or feel the control module click or anything to show the relays were working...

[eugopnosaj 0]

OK so the plot thickens, went to test it all again as I wanted to be totally sure that it was all functioning and giving power when it should, I was getting power as the temperature was going up, thought what the hell and plugged it into the fan and woooooosh, they spun into life...WTH

 

So something is working and something is temperamental, ideally I could do with being able to test my controller on another VR, or possibly it could be that a sensor is faulty and throwing up incorrect values for the controller?

[Jim 2]

If I had my car back from the garage I'd happily let you pull bits off mine, seeing as you don't live a million miles away.

[fla 9]

Where did you put power to the fans when testing? Direct to the back of the fans or via the control box? I'm thinking it might be the wiring going into the fans directly that may be the culprit. You can try connecting a meter to the loom from the fan controller and getting the car up to temp to see if you are getting 12v there.

[eugopnosaj 0]

I tested the continuity on the cable and it was fine, there was 12v to the red/white cable at approx the correct temperature, and then red/black again at the correct temp, I never got any voltage showing on the red/green however.

 

At one point the red/black was showing no power even though the temp gauge was showing 110 degrees. Also when there was power on the red/white (1st stage and aux pump/after run) as soon as I killed the engine the after run wouldn't come on and the aux pump was off?

 

As I was getting power the second time around I plugged the connector back into the fan and they spun into life, disconnecting the rad switch so it got to a higher temp and plugging it back in the high (full) speed came on and then switched off, turning the low speed on every now and then.

 

So its still not conclusive whether it is the control box or the fans????