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Radiator fan / air con relay


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Thought I'd post this in case anyone else has the same problem.

It looks like one relay operates the air con and radiator fan, and it's situated just under the front bumper on the nearside, quite near the windscreen wash bottle.

If you get water on it, it goes "fzzzt" and doesn't work any more = no air con and no rad fan. I figured out the air con wasn't working about two weeks ago, and the rad fan about a week ago (although I was able to prevent anything nasty happening by putting my heaters on full blast and taking it easy in the traffic jam I was in). I recon they haven't been working all winter, but I've obviously had no need for them.

So, take care when filling up your screen wash.

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How did you figure out the radiator fan wasn't working? The temp gauge on the dash always sits just below 90C whilst my scangauge will show a temp of between 80 and 95C depending on how you drive it!

I have always been concerned at the lack of movement in the dash temp gauge :blink:

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Well, to put it simply the temp gauge rose to 110 and the temp light flashed. Fluid checked out ok but the fan wasn't spinning.

Back to the relay, it looks like it's responsible for the air con not working - I'd really appreciate some help if anyone has an idea... the original relay is definitely dead... water stains, rust, broken contacts etc. The part number on this is 1J0 919 506 Q.

Trying to order this from the local VW parts man was met with confusion - he said that 1J0 919 506 K replaced it though, so I got one of those.

It fits ok, runs the fan ok, but has a few different markings on it and doesn't power the A/C compressor.

If you remove the relay and short two of the contacts, the compressor kicks in fine - so it looks like it's the wrong relay.

If Q is no longer in existance, does anyone know what I should have!? Help!

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Well, got the Q and fitted it. Air con still doesn't work, so it looks like the K was a correct replacement.

Back to the drawing board then. To clarify:

When you press the A/C switch, the ECU (I assume) sends a short/subtle throttle boost to the engine in anticipation of the compressor kicking in. But the compressor remains unstarted.

When you short the pins on the relay plug for the A/C, the compressor kicks in ok.

Guessing there may be some wiring problem between the ECU and Compressor??

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Guessing there may be some wiring problem between the ECU and Compressor??

Looks like it. The A/C switch could be broken maybe?

Does anybody have a wiring diagram for the GTi? It may be useful to see the what circuit is used to energise the relay...

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That's the thing, the switch can't be broken because when you press it, you hear the revs raise slightly in anticipation of the compressor kicking in - although it doesn't!

Working on getting a wiring diagram at the moment. I have a guy working on it who's determined not to be beaten by the Germans!

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  • 2 weeks later...

Guy who was determined has now given up.

I've got further with this and found out what the problem is. Apparently when the relay got corroded something must have shorted and two wires that are buried deep within the dash are burnt out.

The dash is now out, the wires are being replaced, and I pick it up tomorrow.

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  • 1 year later...

// Thread resurrection alert //

I had the exact same symptoms as above (AC switch illuminating, revs picking up but no compressor kicking in). I took it to an aircon specialist and he checked a few things including the system for leaks etc and believed that it was an electrical fault and likely to be the fan control module so I bought one (part number 1J0 919 506 K) off Lupoboz.

Fitted it today (1J0 919 506 Q was original part and looked intact - no signs of water damage) and now the revs don't even pick up. No fuses have blown though as in John's case.

So... I have three options

1. The new part is DOA

2. The new part isn't the right one (K not Q) although evidence above is that K supercedes Q

3. The problem is elsewhere

What would you do next? How can I rule out 1 and 2?

The aircon specialist said he had seen a problem like this before on a VW so ordered the part as all signs pointed towards it but it made no difference and it turned out to be a broken wire.

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An independent place that is round the corner from me.

Cheers for that - can rule that out. Wonder if theres a way to test if the new one is working? It is strange that it has affected the behaviour of the problem.

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An independent place that is round the corner from me.

Cheers for that - can rule that out. Wonder if theres a way to test if the new one is working? It is strange that it has affected the behaviour of the problem.

Definatley fitted properly?

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  • 1 year later...

I assume we arwe talking about the control unit that is under the battery? You need to jack the car up and lay omn your back and look straight up under the battery, you will see it there with two plugs fitted.

My fans not working so I tested the fan by giving it direct power from the battery to both terminals and both low and high speeds work. I then plugged it back in and fitted a new temp sender, still no fan. Then I jumped the two contacts on the plug that connects to the temp sender and can hear the control unit under the battery clicking so I am guessing that all is fiune until the relay in the control unit gets involved and then does not send the power to the fan.

I have found GSF sell the control unit far cheaper than VW (£40-£50 instead of £80) and when I have the spends I will get one and see if it solves the problem... I'll update this as and when I get one :thumbsup:

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  • 5 months later...

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