Air Conditioning Problem

Yep, ironically on one of the hottest days of the year, I need some help with an air conditioning problem!

Basically, the air conditioning is nowhere near as cold as it once was, and I can't work out why. When I changed the G263 sensor, the vent temperature would be a constant 3 Degrees Celsius, though now, I'm struggling to get it below 12. It has been around 32 Degrees Celsius here today, though my issue continues to other days when the ambient temperature is much lower. The air conditioning is technically working as the compressor duty increases, the coolant fan kicks in and the air temperature is reduced, just not enough.

I've scanned the HVAC module with VCDS, and there are no errors.

I've taken a look at some key measuring blocks too, although all look to be good. I'll record some key points below. Measuring block is M and the zone is Z. The following values are taken with ECON off, temperature set to LO, the fan on 3 bars and only the face vents selected.

M1Z1 - 0.645A - Indicates compressor is in control mode.

M1Z2 - 65.5% - Compresor load, indicates compressor is being controlled.

M1Z3 - 43% - G65 signal ratio pressure signal, 12% to 87.5% indicates pressure is within the permissible range.

M1Z4 - 14.2 BAR(A) - Refrigerant pressure, 2.6 to 29 BAR is the permissible range.

M7Z2 - 15 Degrees Celsius - Middle vent temperature (this used to be around 3 Degrees Celsius).

M7Z3 - 18 Degrees Celsius - G263 evaporator temp (this used to be around 3 Degrees Celsius).

M7Z4 - 36 Degrees Celsius - Fresh air intake duct temperature.

I understand how refrigerant loops work, but I know very little about the refrigerant itself - does it age or stop working effectively? Any advice or suggestions would be much appreciated.

Regards,

Matt.

Hi Matt i was out in the storm on sunday and i noted my zircon was cool but not cold. I suspect it needs a gas top up so I'm going to get my friendly zircon engineer to look it over. I'll let you know the out come. cheers mike

Can't help with the problem Matt, sorry. But I wanted to add that I had the aircon refrigerant replaced/regased the summer prior to you buying the car.

Hope you get it sorted. I'm sure you will

It really could just be a coolant leak, the presure stays in there a little even with a leak but it could be gas instead of fluid.

My money would be a small leak needing a refil wih some "leak colouring" to show where the leak is (if there is one of course).

Steve B

I was in the same position this time last year Matt. I took it to a local air conditioning specialist and they tried a regas but it didn,t work. Ended up having a new compressor fitted which made it icy cold again.

Ta
Dave

Birchall said:

It really could just be a coolant leak, the pr a little even with a leak but it would be gas instead of fluid.

My money would be a small leak needing a refil wih some "leak colouring" to show where the leak is (if there is one of course.

Steve B

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I had a coolant leak last summer due to a faulty part that failed within months of fitting it from new. The temps in Croatia were silly hot, and the ac was really struggling to get cool air. WOM Automotive did say the coolant leak was more than likely the cause. Replaced with an original Audi part and the climate control has behaved itself ever since.

I have the G263 fault too, but today was a real test for the aircon, and having it set to 19 in auto, I was very comfortable. I don't know what the output temperature at the vent is either.

I'm also looking at getting a regas prior to our summer holiday so I'll check back and update with the findings. Interested if it'll make a difference.

johnmed said:

Can't help with the problem Matt, sorry. But I wanted to add that I had the aircon refrigerant replaced/regased the summer prior to you buying the car.

Hope you get it sorted. I'm sure you will

Click to expand...

John,

Many thanks for letting me know. I had read one of your posts recently where you'd said you'd had the AC regassed, but I wasn't sure if it was the summer you mention or the one before.

Trust you're well,

Matt.

Thanks for the replies, all.

I gather from your replies that the two main things to look for are leaks and correct operation of the compressor.

I'll have a good look in the 'bay tomorrow and see if I can spot anything. That said, this has been going on for at least a month now so I would have expected the 6BAR(A) pressure at resting and the 14BAR(A) when working pressure to have escaped through even the smallest of holes.

Regarding the compressor, I understand that the displacement varies by altering the 'angle of attack' of the wobble plate, and in doing so adjusts the stroke length. As the control works to a point (limited cooling), it clearly cannot be completely stuck, but I wonder if it is possible to become stuck or unable to go above a certain stroke length?

The only other spanner in the works is that I ran the flaps basic setting tonight and although the temperature flap reports no errors in use, when the basic setting is done it produces an error that cannot be cleared until the temperature has been adjusted manually using the climate buttons. Linked perhaps or should the evaporator temperature G263 still be cold?

Many thanks,

Matt.

So, just got back from the Mark 4 AC specialists based over in Slough (recommended by Birchall).

Pleased to say that I was told I'd be throwing my money away getting them to complete a regas. Their checks and gauges showed everything running perfectly and pressure is good.

As I said, I do have the G263 sensor coming up on VCDS, but the car is definitely cool enough.

They also told me that in extreme heat the AC should be set to recirculation so that you're not constantly cooling the external hot air and making the compressor work harder. Made sense to me once he had pointed it out!

Thanks again to Steve for sending me their way.

I didn't have mine on re-circ yesterday and inside it was nice and cool in Auto with the temp at 19deg. The outside temp sensor said 38deg when parked and 31deg when driving.

Ricardo said:

I didn't have mine on re-circ yesterday and inside it was nice and cool in Auto with the temp at 19deg. The outside temp sensor said 38deg when parked and 31deg when driving.

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That's exactly how I usually drive, without it on. Anyone usually using re-circ in hot weather?

On Auto, without re-circ, at 19deg, the interior is just right for me - though the rest of the family grab a blanket or two!

Yep I always use recirc in really hot weather - gives the air-con an easier time.

Simon.

wilco184 said:

John,

Many thanks for letting me know. I had read one of your posts recently where you'd said you'd had the AC regassed, but I wasn't sure if it was the summer you mention or the one before.

Trust you're well,

Matt.

Click to expand...

I've slept since then. Sorry. I'm good. Hope you are too.

Many thanks, all.

Checked the pressure again today with the car not running. 5.2 BAR(A) was measured, compared to the 6 yesterday. I know pressure will vary with temperature, but some does seem to have gone missing.

As such, I looked around the engine bay and have found a leak between the top of the condenser and the flexible hose from the compressor. There is oil on the connection and what looks to be liquid refrigerant on the radiator surround.

I'll get this changed and then get the AC regassed, and everything should be back to normal. As I say though, it must only be a tiny leak as this has been going off for a good while now.

Many thanks for all the help.

Regards,

Matt.

wilco184 said:

Checked the pressure again today with the car not running. 5.2 BAR(A) was measured, compared to the 6 yesterday. I know pressure will vary with temperature, but some does seem to have gone missing.

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The temperature was (probably) higher yesterday, hence the lower pressure today. A small amount of liquid refrigerant vapourised will make a big difference to the pressure (its boiling point will not be too far away from ambient).

RAB

Just a quick question on that RAB what pipe do you top up with as I bought a can with the gauge but don't know which one to use it on the big pipe or the small one

Any help is much appreciated

I don't think it matters but the two connections are different sizes. How do you know how much to add?

RAB

I have a gauge with marker on the pipe

The charge valve is on the larger pipe. Not sure what the other valve is for - safety? The fill is normally done by weight.

RAB

RAB said:

The charge valve is on the larger pipe. Not sure what the other valve is for - safety? The fill is normally done by weight.

RAB

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I'm not entirely sure, but I've read that its possible to measure the HP and LP sides with the compressor running to ensure it's functioning correctly - hence the need for the two valves.

Regards,

Matt.