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Just had a letter from my VW dealer suggesting that the air con on my Passat should be serviced every 2 years at a price of £89.95. Is this yet another way for dealers to make money or is there any validity in the idea? My Passat is 4 years old and the air con (climate control) works perfectly.
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As long as you run the AC compressor frequently and keep the drive belt correctly tensioned it should last for years.
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Read HJ's FAQ's in red box to your left<<<<<<
My advice is to leave well alone if working ok.
IMO it's arguably a dealer money extractor anyway if the a/c in my own car should fail, a main dealer is the last place i'd take it. An a/c specialist would be my choice.
Discussed many times in backroom. Search in the forum search facility to your right>>>>>>>>>>>
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What a spendid example of rip-off Britain! Where I live any street corner motor workshop will check for leaks, gas up the Freon as req'd and check the belt for about 5 quid exra on top of the normal costs for a service.
Unbelievable the length UK companies will go to separate you from your moolah.
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What a spendid example of rip-off Britain! Where I live any street corner motor workshop will check for leaks, gas up the Freon as req'd and check the belt for about 5 quid exra on top of the normal costs for a service. Unbelievable the length UK companies will go to separate you from your moolah.
Totally agree, though in defence, A/C is almost as essential as brakes, tyres etc. in the tropics and almost every car will be equipped with a FF or aftermarket system. Therefore having your A/C checked has become as common as having your brakes checked, oil changed* etc.
In the UK, A/C has only become common place in the last few years, before that it was only luxury/top end car that had A/C as standard - so I expect the service infrastructure will be relatively limited. If a few years time when the current crop of cars start coming outside the dealer networks for servicing, we may see changes.
* Knowing the way some cars are maintained in the developing world perhaps not that common after all!
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I have a self-imposed two-year servicing schedule on the A/C in two of my cars. A/C is complex and expensive to repair; a stitch in time . . .
£89.95 is a perfectly reasonable price -- the same as I have been charged by the mobile-service guy who has done my cars.
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. . . and in my search for a mobile service to replace the one I have been using (he has moved to Surrey), I found
www.aircool.biz/
at which they say
"How often does my a/c need servicing?
Usually once every three years it is recommended to have the a/c drained and refilled with new refrigerant, air conditioning refrigerant is hygroscopic, and absorbs moisture (one of the main reason for poor performance in car a/c systems) through the rubber hose sections, its also these rubber hose sections which allow the gas to migrate from the system, causing natural loss."
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Roger Jones I can't let you get away with that 'three year servicing' con. The gas in an AC system is totally enclosed and maintained above atmospheric pressure whether the compressor is running or not, so ingress of moisture from the air is impossible. As for gas leaching out, refrigerent gas has big molecules and the rate of leaching, if any will be infinitesimal. Under use is the biggest bugbear for auto AC because as so many before me have indicated, the circulating gas carries with it the lubricant for the compressor and associated seals, lack of use allows the latter to dry and shrink and harden so the gas leaks out.
I stand by what I wrote in my post earlier.
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Even though the system is under pressure, ingress of moisture is still possible. The manufacturers can verify this, and that is why they include a drier in the system containing a dessicant to absorb moisture.
Unfortunately, there is gas leakage over time, though it is reckoned to average 5%/year, and again the manufacturers will verify this. Due to the EU's dislike of r134a refrigerant, they wish to see it banned by 2010, so have asked the manufacturers to look for alternatives. As a sop to the EU, they went back to them with an 'Enhanced R134a system' with promises to reduce annual leakage rates to something like 2%. So static leakage is very real.
The main leakage points are the rubber hoses, O rings, and especially the front seal on the compressor that has high pressure gas on one side, and ambient pressure on the other, and through which has to travel the rotating shaft. This is why fridges and the like have extremely small leak rates, as they have copper pipes, brazed joints, and hermetically sealed compressors, where the motor (and therefore the rotating shaft) is contained in the metal compressor housing.
As for lack of use, I'm not sure that holds much water, as I've got boxes of O rings that I've had for a number of years, but none of them have fallen apart or desintigrated while they've been in my toolbox.
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I use hermetic compressors at work, ranging from 3cc to 26cc. There is no such thing as a hermetic compressor, in real terms. There are at least, depending upon the compressor design, 5 intrusions which can leak.
1 Suction line
2 Process line
3 Hot gas discharge line
4 Electrical connection
5 Welded seam.
Car air-con is basically a split system, the "hot" side is in the engine compartment, the "cold" side is part of the interior ventilation system. The gas does not absorb moisture, the oil does. Possible leakage sources are:-
Mechanical joints.(non brazed)
Flexible pipes.
Shaft seals.
R134a will be around for years. The "environmentally friendly" R600 range have been ruled as unsutable by the USA because of their inflammability.
The drier/molecular sieve/receiver fitted to most a/c systems is oversized for initial installation, and has a large over capacity to deal with any moisture ingress.
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Con man I am not. You can see that it was a direct quote from another site. I'll invite the owner of that company to participate in this discussion, as he has now replied to my e-mail making contact with a view to giving him work.
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Dave N is right, molecules of R134a gas are smaller than molecules of the old gas R12(also known as freon, which was the gas installed in all vehicles built before 1993), and require a special 3 layer barrier hose, despite all of this, gas does leak naturally, up to 20% per year.
to keep your ac in tip top condition it is important to keep the system dry, gas, and the oil suspended in it, react with moisture to form acids which can damage the internal components.
No one will force you to have it done, its your choice, but there is a positive and noticeable benefit, the gas level will certainly be low at 3 years, and a recharge will put the crispness back into the air from the vents.
I only want happy customers!, dont have it done if you dont want to!
regards
Steve angell CAE MIMI
Aircool AC Ltd
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The drier is mainly to mop up moisture after the initial charge and after any top up. If you run your AC frequently and keep the condenser clean it will last for many years. There are industrial cold store systems with old reciprocating compressors which have been chugging away for many years with only a five yearly inspection .
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try running it up and down the M1 for 30,000 miles and see how it goes!!!
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Aircool thanks for your reply, I yield to your superior knowledge of auto AC systems. Would you agree though that apart from maintaining the correct gas charge it is potentially risky to open up the system for maintenance if it is operating correctly just because it is three years or whatever since the last overhall? If refrigerant leaks to the extent you have indicated are there not better, less porous flexibles available. Going back to the industrial plants with R134a they too often have flexible hoses from the compressor discharge and leakage here is not a problem.
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You're not really opening the system, as at no time is it open to atmosphere. It's either having the gas recovered, being vacuumed or charged.
Sure there's better hose material available, but that doesn't sell cars. But as mentioned before, the hoses aren't the only problem area. Also, the engine bay is a pretty hostile environment regards temperature and vibration. A lot of cars don't carry a lot of gas, many now only have circa 500g, so a modest loss can make quite a difference.
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Thanks Thallium81, once again Dave N is spot on, fixed plant commercial refrigeration is very different to car a/c, although the physics are the same, the operating conditions are much more hostile, for example gasses used in commercial plant such as R404(i think thats what they use) and R600(hydrocarbon, not to safe!) suffer from high head pressure in cars due to high under bonnet temperature, i bow to your greater knowledge on the commercial side, it is very different, and i dont know a great deal about it!
regards
Steve
PS. as far as hose goes, it is needed because the engine mounted pump(compressor) moves with the engine, and the body (where all the heat exhanging is carried out) does not, a problem not found in plant. most manufacturers limit the amount of rubber hose to a minimum, and the hose used is the best possible within the confines of cost.
I understand the next generation of car ac systems due to be rolled out in 2007 will be CO2 filled systems using all stainless steel piping, at least it will look nice!
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Cheers Aircool I've got the picture, thank you. You're right about industrial systems, they are gradually changing to ammonia;(I cant remember the R number) especially in rotary comps. but it is considered too poisonous for domestic or auto plants. Anyway after reading yours and DaveN's posts I shall keep my car's AC fully charged and give my cold store engineer mates the benefit of my new knowledge, especially the one who is moaning about the rubbish AC on his four year old Lexus ;). I'll shut up now.
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Thanks for the discussion, it helps sharpen up the memory again!
regards
Steve
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