Advice: RS2 Aircon

**MikeLarwood** · 17 November 2008, 13:47

It's usual for the air conditioning to be better when the engine's spinning, but not that bad I don't think. Maybe the pump is cream crackered?

**S2central.net** · 17 November 2008, 13:58

If the ambient display is saying 60 celsius then something is wrong...

On those climate equipped LHD RS2 the ambinet display wiring goes thru the head unit of the climate controller... Either its gone mad, has a bad connection or the ambient sensor is bad...

You should be able to pull error codes from the climate unit by VAG-COM... There is also a trick (google it) to pull codes on the head unit display - I can't look for it right now...

Paul

**GT500** · 17 November 2008, 16:27

Paul, how do you know its a lhd full climate system?
sounds like turney knob rhd with "setting 4"

**S2central.net** · 17 November 2008, 16:54

uhhhhhhhhhh ummmmmmmmmm - yeah see your point actually - hadn't spotted that 'setting 4' reference and thought of the manual fan speed...

**simon44** · 17 November 2008, 22:09

Yes, sorry, its a RHD RS2. The ambient temp sensor is fine when driving, its just that if the engine continues to run when at standstill it starts to rise which it continues to do until it reaches 'E'. When I am driving at 30/40 mph the aircon can manage some cool air.

It had an aircon recharge in the summer and then another a month ago once we had fitted a new dryer. The system ran a print out saying all was well both times.

Cheers

**johne** · 19 November 2008, 23:50

It should do better than this making cold air at idle - as long as the radiator fan is on, which you say it is.

Could be the compressor or not enough gas. You need to put an air-con pressure gauge on the high port which is the one on the radiator iteslf. Expect around 50psi with the compressor not running, 200psi when it is. Readings are very temperature sensitive so we're talking approximate here. If you get more like 50psi and 50psi add more gas. If no improvement then it looks like new compressor. Does the pipe that the gauge is attached to get too hot to hold?

Could also be a blocked restrictor but this would give a very high compressor on pressure reading which would cause the system to shut down.

You say the fan cuts in immediately, it should, but at what speed? Does it go to a higher speed after it's been stationary idling for some time - and I know this is difficult to distinguish - but not because of higher water temp?

John

**simon44** · 24 November 2008, 21:16

Hi John, thank you for your note. I'll look into these suggestions and report back!

Many thanks

Simon

**simon44** · 11 June 2009, 09:33

Hi, I just wanted to report progress. We cleaned out the valve in the pipe nearest the windscreen/interior and together with the new dryer, which was replaced a while back, I have stopped getting the warm moist air flowing (which caused the windows to mist up). So this is a step forward. We have also removed and cleaned the red and green safety switches and noticed that the switch with the red end has a crack in it, so this is the next thing we need to replace. Will report back!

**S2central.net** · 11 June 2009, 11:37

tell me what the red and green switches are doing - open or closed - with your aircon running

**red leader** · 11 June 2009, 17:37

I've just regased my s2 and had the same problem.. Check out how much dirt is on your condenser.. I steam cleaned mine and was perfect..

**simon44** · 15 June 2009, 20:55

Before I replaced the red switch it was telling the aircon pump to turn off when the pressure built up. I've replaced it only to discover that there is green refrdgerant leaking from above the green switch, from the circular part that the switch screws into. So to replace this part I need to buy a new condenser, but we fitted a new one less than a year ago, sourced from VAG Parts.

Has anyone ordered one and it has arrived without the new 'switch' pipe? I never saw it pre-fitted but ordered it and it was sent to the mechanic direct.

Paul, in terms of the green switch I think this controls the fan/fan speed - the fan is working but I'm not sure to what speed.

On cold start up, the aircon is nice and cold, the pipework develops condensation on it, and then when the engine temp approaches 90 degrees, you start to hear 'heaving breathing' noises followed by a surge of warm air that develops into hot air.

Many thanks

**johne** · 16 June 2009, 21:44

Simon,

AFIK the condensor comes with the pipe already welded to it. Once you remove the red or green switch you have a standard schrader valve underneath which should let you remove the red or green switches without loosing much R134a gas. I suspect you can unscrew the valve itself just like a tyre one but as it's normally held open in service by the switch there's not much point. The only sealing mechanism for the switches is the O ring which I'd try replacing before anything else more drastic. Lubricate the seal with PAG or POE oil before refitting it. If that doesn't work, I'd use a can of leak sealer.

The green switch is set to close at 15 bar (approx) and brings the fan in. The red switch is set to open at 30 bar (approx) and disconnects the compressor. The red switch should never operate in normal use, it's there to protect the system from damage should there not be enough cooling or the restrictor becoming blocked. If the red switch were to open as you appear to suggest it does, then I'd expect you to get that blast of warm muggy air you mention.

When the compressor is working it will compress and heat up the gas. If that heat isn't removed by the condensor radiator the pressure will continue to rise and rise until the red switch turns everything off. The green switch is set to turn the fan on as the pressure rises to make up for the fact the car isn't moving. If the condensor is dirty as someone else suggested or the restrictor is blocked then the fan on the green switch setting can't cool the condensor enough and the pressure will continue to rise up to the red point.

In normal use, given the lower output from the compressor at idle and the car stationary, the fan cutting in with the green switch is sufficient to keep some cooling and stop the system reaching the red switch cutoff point.

John

**simon44** · 17 June 2009, 13:01

Hi, many thanks John, really helpful. There is a small seapage from the housing that holds the valve. A very small amount of green coolant creeps out of the circular bit of pipe above the valve, on the outside. I've cleaned it off and then watched it reappear and then run down onto the green switch.

Looking into the condenser, this was replaced a year ago by the garage I use - part number TSP0225170, I think this might have been supplied by GS or Camberley Auto Parts. The Audi part no is 8AO 260 403 AC.

Worringly, there is one on sale on ebay and it looks much slimmer than mine - http://tinyurl.com/m6eyo7[/URL]

Have now spoken direct with Camberley and they think the pipe on the front should have come with it so they are now speaking direct with Delphi...watch this space!

Attached Files

Condenser_overview_.jpg (82.3 KB, 67 views)

**S2central.net** · 17 June 2009, 13:04

Originally posted by johne

Simon,

AFIK the condensor comes with the pipe already welded to it. Once you remove the red or green switch you have a standard schrader valve underneath which should let you remove the red or green switches without loosing much R134a gas. I suspect you can unscrew the valve itself just like a tyre one but as it's normally held open in service by the switch there's not much point. The only sealing mechanism for the switches is the O ring which I'd try replacing before anything else more drastic. Lubricate the seal with PAG or POE oil before refitting it. If that doesn't work, I'd use a can of leak sealer.

The green switch is set to close at 15 bar (approx) and brings the fan in. The red switch is set to open at 30 bar (approx) and disconnects the compressor. The red switch should never operate in normal use, it's there to protect the system from damage should there not be enough cooling or the restrictor becoming blocked. If the red switch were to open as you appear to suggest it does, then I'd expect you to get that blast of warm muggy air you mention.

When the compressor is working it will compress and heat up the gas. If that heat isn't removed by the condensor radiator the pressure will continue to rise and rise until the red switch turns everything off. The green switch is set to turn the fan on as the pressure rises to make up for the fact the car isn't moving. If the condensor is dirty as someone else suggested or the restrictor is blocked then the fan on the green switch setting can't cool the condensor enough and the pressure will continue to rise up to the red point.

In normal use, given the lower output from the compressor at idle and the car stationary, the fan cutting in with the green switch is sufficient to keep some cooling and stop the system reaching the red switch cutoff point.

John

Good description there John - our resident aircon guru

Advice: RS2 Aircon

Advice: RS2 Aircon

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