B5 1.8T air con issues

[Pat D]

Anyone familiar with what would cause the air con to cut in and out roughly every 30seconds and eventually switch itself over to 'econ' mode?

This is happening when ambient temp is very hot, around 45c. As it gets cooler at around 42c it works fine and the air coming out is nice and cold. I can hear a relay switching at the same time when the comp cuts in and out, so I'm assuming it wouldn't be the AC clutch being faulty.

[rynaqui]

Compressor heating up? I suppose heating with the blower on is not effected?

Other than that maybe faulty relay I think

[Error404]

That is probably the clutch relay clicking away. It takes it signal from the climate control unit. Perhaps the interior temp sensor is faulty or if its that hot maybe its out of its range?
You should be able to access the climate fault codes through Vagcom

[kninio]

ac compressor on its way to heaven, happend once before to me before in the end its almost sized , do u have climatronic?

[johne]

Anyone familiar with what would cause the air con to cut in and out roughly every 30seconds and eventually switch itself over to 'econ' mode?

This is happening when ambient temp is very hot, around 45c. As it gets cooler at around 42c it works fine and the air coming out is nice and cold. I can hear a relay switching at the same time when the comp cuts in and out, so I'm assuming it wouldn't be the AC clutch being faulty.

I think you could be on the edge of not having enough gas or the clutch can't hold but there's a couple of things you can check. When it's very hot, is the radiator fan coming on at a fast speed rather than the lower speed it cuts in at when the A/C is on? (Could be difficult to check given that in those temperatures the radiator fan may well be on high speed just to cool the engine). If it is, it could be that the system is dropping out due to the high pressure switch on the condensor and you're just on the limit of what the system can cope with.

Check the compressor clutch isn't slipping by looking to see if both parts of the compressor clutch are rotatating.

If you've got climate control, you don't need Vagcom to look at the fault codes, the climate unit itself will display faults for you.

See: http://12v.org/urs/Climate%20Control...0&%20Codes.pdf

John

[Monkeymagic]

Check the hi lo pressure switch with vcds most common fault.

[ManiacuV6]

I think that the problem is that you get a too high pressure in the refrigerant circuit ( > 30bar) and the compressor is turned off.
YOu need to check the lo and iHi pressure using ai air conditioning refill machine.

[audinut]

over gassing causes this problem too ...

[Pat D]

Cheers for the replies, I'll have to dig out the VAG com cable and see what fault codes come up. I'm sure it'll be over pressure when it heats up a lot. I do however have a whining sound that has been developing over the last few weeks coming from the front and it's on the a/c comp side damn it.

[Monkeymagic]

The clutch on these engines gets a battering as its mounted on the front.
I have a practically new genuine compressor for a 1.8t tt Sat in a box i can sell you but you would need the part number from yours so i can see if its same part.
If not i bought one for a tdi a4 from local factors for 350 and 45 for gas.
That one had seized and wrapped the belt around the crank pulley very messy .

[ManiacuV6]

IF the radiator's fan isn't working is another issue why you got intermitent function.