AC Issue !!!!

[RUM4MO]

I agree with your independent AC specialist that maybe 95 out of a 100 3 to 5 years old car should not need their fridge gas topped up in order to keep them working as intended - but, the car industry's version of AC does contain extra flexible interconnecting pipes so the expected gas losses over a period in time is greater than that of a stationary same sized AC system as it would only be the plastic O-ring seals that would leak, so for the car industry, a figure of 10% by weight loss each year is "allowed for" - so that is the fact that VW dealerships and others are "hanging their hats on" or using as their "get out of jail free card".

These small and compact car AC systems are filled to a critical level, that means that if more gas is added they will probably not perform to their maximum performance and similarly if they are slightly short of gas - that contrasts to larger commercial systems where there will be the ability to hold extra gas and so perform at maximum performance over a longer period in time, if legal maintenance requirements did not require them to be opened up. The thing is that most people do not notice a slight drop in performance as the expected/allowed for gas losses take place, only doing something about it when the system is really short of gas and starts making unusual noises and stops cooling the cabin down enough.

Not much of this concerns your car as it obviously has a leak, in a sort of defence of your supplying VW dealership, they may well have found that the AC was not performing as good as expected at the pre-sale point, and so recovered the remaining gas charge, applied a vacuum which dries the system out and checks for leaks roughly/crudely - if the required low pressure limit can not be achieved within the required time, that system has failed, has a leak and should not be recharged with gas until it has been repaired. Only problem being, if there was a small leak at a bonded joint, applying a vacuum quickly might well have closed that leak and so masked it first time round, then with gas back in and the system running that small bonded joint would start leaking again and might now have developed into a gross leak which now does not temporarily seal while under vacuum test. Some leaks are just "running leaks" and not so easy to spot, though again not in your car's case.

I've just written all that down so that you can maybe better understand what could be going on, and so have a slightly better experience when visiting your VW dealership, that is all.

[chrisb1357]

Update:

Car went into VW on Friday and they had the car allday. They have said the evaprator needs to be changed after tests and leak test they can also trace the leak back to be behind the dash / glove box area so they are sure its the evaprator. VW have approved them to carry out the repair under the Das WeltAuto warranty so the car is booked in for 2 days this week for a replacment evaprator

[RUM4MO]

Good result, replacing that should sort this out for you.