How to check if A/C is functioning

[og77]

Hi all,

My '64 6C is under warranty for a few more weeks after buying it from VW used last summer. The aircon was serviced and regassed just before I bought it. I've since done only around 3200 miles in it, rarely using the aircon except to help demist the windscreen when I've got in the car still wet from a shower, and for a few weeks in the summer. I'm more of a short-distance driver, generally no more than 40 miles on any given journey, and more often less than 10.

I've noticed the air con isn't making me freezing like it used to. In fact, over the Easter weekend, when temperatures soared, it was only when I arrived at my destination after a 30 minute drive dripping with sweat and thinking I'd hit early menopause that I opened the door to find it cooler outside than in.

Since then, I've attempted to use the A/C a bit more to see if I was just adjusting badly to the sudden heat, and to be honest, I can't tell. I've had it set to max cold, with recirculation turned on, and I'm not chilly. I'm always chilly.

Is there any non-techy way to do a basic check to see if there's something wrong with the air con, or whether VW will charge me the £60 or whatever it is for investigating a non-existent issue? Bearing in mind the car is off to the garage on Wednesday and I've already looked like an idiot once (other half advised me that one of my reversing lights was broken, and after swapping the bulb, still no joy. Turns out that bulb is a FAKE, and I looked very stupid, but got a free car wash whilst it was in the garage. So not a total loss.)

Any help appreciated!

[RUM4MO]

Whoops nightmare concerning the second reversing light!

AC, when it is running, and the outside air temperature is 16C I measured the centre vent temperature to be 7.8C - that is with auto AC, if you have manual AC you should be able to see temperatures a lot lower, as listed below which is just a generic statement concerning car AC systems.


"CHECKING AIR CONDITIONING PERFORMANCE

1) With engine fully warmed up, set system for minimum temperature and maximum fan speed, check that the high pressure (small diameter pipe) is cold and the low pressure (large diameter pipe) is warm – this can be done at the point that they pass through the firewall.

2) as above, but with an ambient temperature above 4.5ºC, measure the temperature of the air coming out of the centre air vents – it should be 19-22ºC less than the ambient temperature.

3) Always add charge into the low pressure (large diameter pipe) side with system running – keep car doors open to allow for continuous operation of compressor."

Now you problem will/could be, that VW ignore the fact that refilled that system a year ago, but if this is on record, then if that AC system is working as designed, with no unusual leaks, then after 12 months it should still be chilling as well as it did when refilled prior to being sold.

Edit:- that car will still have the older type of fridge gas in it, ie R134a, so still cheaper than the newer gas to refill.

[og77]

Thanks Rum. I annoyingly haven't had time to buy any sort of thermometer (not sure the thing we stick in the chicken will be any good!), but I'll have a week or so to check it myself if they say nothing's wrong. I'm pretty sure that after 30 minutes of driving with it set to the coldest temp (manual), I should be turning blue at the extremities.

There's a note in the service book that shows the a/c service. At a minimum it was regassed as I test drove it in the summer and it was hissing and not cooling at all, and now it isn't hissing, but certainly did cool for the whole of last summer. My previous car I bought used and kept for 6 years and didn't top up the gas, and it was still working fine, so I'm a bit disappointed, to say the least.

[RUM4MO]

I'd think that the chicken thermometer will start at too high a temperature to be of any use here unfortunately.

Make sure that you don't get fobbed off with the "you should get it serviced every year" guff as that is rubbish, though it seems like some of the newer systems need this attention which I'd think is another major fail by the motor manufacturers when starting to use the latest refrigerant, really a good opportunity to upsell this additional service.

Buying and setting off a detergent "bomb" inside the car every 2 years is a good idea though to try to kill off any nasty "beaties" breeding in the moist zone at the evaporator in the air box.

[og77]

VW have reported that the system is completely empty of gas. They're telling me it's likely a stone that's put a hole in the condenser. They've therefore done an a/c service to refill it and added dye to something, and I'm to drive around with the air con on for two weeks to see if they can find where the leak is.

Which is annoying, because I work from home and don't really drive anywhere, but it looks as though I'll be just tootling around for the hell of it every evening.

b*******s.

[RUM4MO]

That is very annoying as now it sounds like the damage was caused by an outside influence, ie not a manufacturing defect - but it might just end up being a leaking evaporator which is inside the car and so can not be easily damaged by an outside influence.

Very sloppy job being done by that VW main dealer, and to the standard that seems to be expected wrt AC fault diagnosing, but what can you do while under warranty, another forum member or maybe even a member of another VW Group motoring forum had a similar problem, supplying VW main dealer just refilled the system and sent them on their way, getting annoyed by the refill not lasting very long they took the car to a proper AC repairer, they found the fault quickly which was the evaporator - VW could not just accept these findings, so the VW dealership carried out further investigation and agreed that it was the evaporator - which is a big dashboard out job.
The UV dye is added in with the R134a fridge gas, then the "fixer" can shine a UV light around all possible leak sites and detect the sprayed out UV marker which escapes with the system oil and fridge gas.
Now, so far all they are doing is an investigation into where the leak is and if it is covered by warranty, if you could be bothered with the faffing about, and it turns out not to be a repair covered by warranty, you could say "thanks" and take the car away and get a proper AC repairer to fix it probably for a much lower cost to you.

[og77]

Thanks Rum, always appreciate your knowledgeable input! If it's not covered under warranty I'll definitely be taking it elsewhere, although presumably if I can find an a/c specialist within 5 miles to give me a lower quote, I can take that back to VW and they'll have to match it. We'll see how it goes. I read the other thread with interest and trepidation, but I think persistence is key.

I need to check when I pick it up that they're not going to mess me about - 2 weeks from when I pick it up is outside of the warranty period. But presumably as the fault was reported within the warranty period, it'll be ok. Presumably.

[l3rady]

Just adding my experience with Air con with my 2015 6c.

After two years of ownership the next summer the aircon was no longer working. Took it in for a regas and their system showed that it was completely empty so the mechanic suggested there might be a leak. The system did the clean and pressure test and all went fine so the car was regassed successfully. A year and a half later the aircon is still working optimally.

I asked the technician why would the system be empty if there is no leak and he asked me during the previous winter did I use the air con at all. I, as like the OP, very rarely use my car and in the winter never once used the AC. The technician was like ahhh, that'll be why. He advised me it was like "use it or lose it" and if the AC is left unused for prolonged times the gaskets and seals in the system start to retract and can then cause a gap to form and vent the gas. He advised me that even if I don't need the AC it is advised to use it at least once a week to keep the fluids in the system moving and keeping the gaskets lubricated and under pressure to stop them failing.

As I only really use my car once a week to do the shopping I basically keep AC switched on all the time in the car. Just because it is on doesn't mean it has to blow cold air. You can still have it on running with heat. If I take the car on longer runs or for other drives mid-week I then turn off the AC knowing that it has been run for a bit each week. A year and a half later the AC is still working so there is no leak and what the mechanic told me seems to hold up to why the system was empty.

[og77]

l3rady - interesting! That may well be it. Or rather, I hope that's it so that all I've got to pay for is the a/c service and not however many hundreds of pounds it'll cost for a new condenser, or however long VW would need my car for to take the dash out and replace the evaporator under warranty. Not to mention it'd never feel the same knowing it'd been through that sort of trauma!

You have given me hope!

[SRGTD]

I switched the a/c on in my GTI the day I picked it up (01/03/2016) and it’s never been turned off since.

It’s always worked as intended, which might be down to it being used continuously?

I’ve also never had issues with condensation / windows misting up in the autumn / winter that some other owners experience. I’ve put the lack of steamy windows down to the dehumidifying effect of running the a/c all year round.

[RUM4MO]

Just adding my experience with Air con with my 2015 6c.

After two years of ownership the next summer the aircon was no longer working. Took it in for a regas and their system showed that it was completely empty so the mechanic suggested there might be a leak. The system did the clean and pressure test and all went fine so the car was regassed successfully. A year and a half later the aircon is still working optimally.

I asked the technician why would the system be empty if there is no leak and he asked me during the previous winter did I use the air con at all. I, as like the OP, very rarely use my car and in the winter never once used the AC. The technician was like ahhh, that'll be why. He advised me it was like "use it or lose it" and if the AC is left unused for prolonged times the gaskets and seals in the system start to retract and can then cause a gap to form and vent the gas. He advised me that even if I don't need the AC it is advised to use it at least once a week to keep the fluids in the system moving and keeping the gaskets lubricated and under pressure to stop them failing.

As I only really use my car once a week to do the shopping I basically keep AC switched on all the time in the car. Just because it is on doesn't mean it has to blow cold air. You can still have it on running with heat. If I take the car on longer runs or for other drives mid-week I then turn off the AC knowing that it has been run for a bit each week. A year and a half later the AC is still working so there is no leak and what the mechanic told me seems to hold up to why the system was empty.

So, lets see/think, you switch the AC on, which is only you allowing the system to use fridge chilling to cool down/control the cabin air as and when necessary - and that counts as using it, I don't think so, the temperature controller will try to control the air temperature by blending outside air with heated air, when it fails by a few degrees, the chiller compressor will be commanded to increase its displacement and deliver meaningful volumes of compressed fridge gas into the evaporator. Remember something that that VW tech had not known or had not bothered to think about, all these modern cars have a fridge compressor that is continuously driven by the auxiliary belt, when it is not required for proper chilling purposes, or you have switched of the AC function, a small volume of fridge gas as well as oil mist is being driven around the system, the main reason for this is to always maintain enough of a flow of oil mist round the system to keep the seals and flexible pipes "wet" and so in a better condition to prevent excessive loss of fridge gas, a knock on effect will be to help "trim" off slightly over temperature air.

My wife's August 2015 6C Polo has only had the AC running a few short times in its entire life - and the gas level/charge in the system, at least when last checked by me last summer, was okay. Similarly my 2011 S4 and it has a worse life as that car only gets used now and again something like once a month on only longer journeys. My daughter's late 2009 Ibiza unfortunately, while I was looking after it for her, did not get used for long periods in the winter (wide low profile wheels) and it did end up needing me to recharge it a year or so ago.

[og77]

Thanks everyone for your input. The car is back with me, recharged with a dye added and blowing cold air. I'm not sure I like the garage's approach though, as they said to drive around for two weeks and then if it starts not to cool properly again, bring it in.

That sounds stupid. What if it's a slow leak. Presumably it's not a hole in the condenser as they will have been able to spot it. I'm hoping they're not trying to wait out the warranty period. I am a suspicious person.

On the other hand, if it did just seep away because of dry seals as a previous poster mentioned, I've saved myself £80 on their standard air con service charge as they've charged me £60 as it falls under fault finding. So maybe it's a win.

Can I just buy a basic UV torch from Amazon and inspect it myself? I mean, I have no idea what I'll be looking for, or where to look, but it might be fun.

[RUM4MO]

I think that you can buy a UV torch and maybe UV filter protective glasses, maybe as a kit, I'm sure that if you use the usual route to find that out it will provide you with source.

Edit:- I'd be a bit concerned/annoyed as well in your position.