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Crustynuggets

Air Conditioning Service

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Ok folks,

as some of you know, I'm new to this forum and the proud owner of a lovely, one year old Avensis. It's my 3rd Toyota, the first being an 02 MR2 and the second being an 05 Corolla.

The point of this post is to mention the seemingly increasing trade in air conditioning service. Even the likes of Kwik Fit have their fingers in the pie these days.

My view is, it's mostly a big con! Here's why......

Air conditioning systems are sealed. Sounds simplisitc, but it's true. Basically, just like in a domestic fridge (yes, that is an air conditioner!) you have 3 main parts -

The Compressor, The Evaporator and the Condenser.

I'm not going to bore you with all the principles of how it works, but basically the system houses a refrigerant gas in a vacuum. The system cools the air in the car by changing it's state from a liquid to a gas, and in doing so draws in heat in a constantly changing cycle. In effect, the system is not adding 'cold', it is removing 'heat'.

Now, the reason I mention the vacuum is important when I comment on these 'air conditioning services.' A vacuum is just that, a vacuum! It's a sealed system, meaning it'll either work or it won't!

If it's leaking it needs fixing before any of this so-called "re-gassing." In other words, if your air conditioning / cimate control is working fine, NO NOT get sucked in to this 'air conditioning service'. Other than checking / replacing the cabin filter, which I'm sure you good people can all do yourselves, the system is pretty much maintenance free. If possible it's a good idea to also check the condenser and evaporator coils to make sure they're clean, but to be honest I've not ever seen real dirty ones on a car before.

I should mention what a lot of others have said - use your air conditioning! The more you use it, the more reliable and efficient it will be! The gas inside the system also contains lubricants which seal the various joints and connections in the system. The more they move around, the better the system will work. To be honest, I keep the A/C on in my car. Sure, running the system will use a bit more fuel (although these systems are getting ever more efficient), but in my view it pays dividends in how the cabin temperature is kept as I want it and maintains the integrity of the system.

Remember, the A/C doesn't just cool, it de-humidifies, so even in winter you're quickly going to get rid of those misty windows!

If it does start to feel like it's not getting cold, then I'd suggest you do have a refigerant leak, which should be checked out before and re-gassing takes place. Like I said, this is more likely to happen if you don't use your a/c regularly. Car air conditioning systems run at lot lower pressures than building systems so are more prone to leaks if they're not used.

The moral of this story is 'if it ain't broke, don't fix it!' After all, you don't have a bloke come around and re-gas your fridge, do you?!

Just keep an eye on the cabin filter and use your a/c!

I hope I've not droned on too much and that what I've said may help some of you fine people. :thumbsup:

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I think you have to look at this in perspective.

I agree in theory what has been said but it would be unfair to say the least to compare the air-con system in a road vehicle to a household fridge simply because the environment in which they have to operate are as different as chalk and cheese.

How long would the average household fridge last of subjected to the same treatment as that under the bonnet of a car where it is shook, vibrated, subject to serious voltage variation, extremes of temperature and constantly being switched on and off, having to deal with varying degrees of humidity, etc, - the list goes on.

In reality car air-con systems are almost certain to develop leaks over time and if a £40 top-up sorts the problem for even a year it going to be cheaper than say replacing a compressor at around £500 plus. Due to the hidden installment apsects of a car air-con system the labour cost are very expemsive indeed.

I don't know about all fast repair outlets but my local makes the claim if a service doesn't make the system colder you don't pay so what has the average car owner to lose.

You also have to remember it is very are for a household fridge to be switched off (possibly once or twice a year) yet the air-con system in a car is switched on and off every time the car is used whether you like it or not - that's assuming you leave it switched on comtinously. So if I use my car purely for travelling to work 5 days a week and I choose to keep the air con switched on it means it will go through at least 200 cyles of being switched on and off.

Yes I agree if it ain't broke don't fix it - sadly many people take the opposite view of "I'm gonna keep fixin it till it's broke":)

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Yes, but my point is, keep using your a/c and you shouldn't need to have your system regassed bar any serious defect.

I'm not a fridge engineer, I'm an air conditioning engineer so it frustrates me to see certain parts of the motor industry push "regassing" when it's not needed, and if it is needed then the underlying cause needs to be sorted first.

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Domestic fridges and freezers are hermetically sealed, there can be no escape of gas.

Car AC systems are most definitely not sealed. There are many flexible joints that can and do seep, the compressor crank shaft "front seal" being the most common point of leakage. It is an accepted fact that systems lose anywhere between 5 and 20% refridgerant yearly. They all leak... some more than others. I agree about keeping the system on all year round though.

Jamesbelfast... I haven't owned a car where the AC runs every time the car is used. If the AC is off the compressor doesn't engage and run, so no circulation of refridgerant. That's the biggest cause of AC problems, lack of use.

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Well I am no engineer or clain to know much about these things, but I for one have my AC on all year round. For the most part it is on the lowest fan setting so I am not draining my mpg too much (I hope!!) and I have had my car now for coming up to 6 years. It is still nice and cold and works a treat (touch wood!)

I do believe that if you use it regularly, you are stopping things from seizing up/not working etc. I did know about the lubricants that you mentioned and thats why I use it as often as I do. I too am not convinced by these AC servicing places. And I also love the fact that the AC works a treat in the winter too - I do think the Avensis heats up pretty quickly!

Thanks for the posting, very informative!

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Jamesbelfast... I haven't owned a car where the AC runs every time the car is used. If the AC is off the compressor doesn't engage and run, so no circulation of refridgerant. That's the biggest cause of AC problems, lack of use.

The point I was making was that the air-con system in a car is constantly switched on and off more often than either a household or industrial system.:)

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The problem with automotive A/C systems are customers use it very rarely, you cannot get the average Joe to switch it on in the winter and that is where the seals/joints dry out and leak gas. We only get to see most customers once a year at service time and the first time they know they have a problem is when the efficiency is poor and does not cool as well as it used to on a boiling hot day!

As I have mentioned on here many times before, and A/C service is more than a Re-Gas, it is checking the system for leaks and re-oiling etc and should be done as part of your routine maintanance, at least every couple of years. I have just issued a pollen filter for a RAV in our workshop that was replaced 9 months ago, it is FULL to a depth of a good 10 mm of seeds and leaves, it completely covers the whole of the filter, I have never seen one quite like it, you don't often have to de-seed your home refigerator :lol: I think the two scenarios, whilst sharing similar technology are chalk and cheese from each other

Kingo :thumbsup:

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I wish I'd never mention the fridge now! hehe!

I think maybe I went off on a bit of a tangent. All I was really saying I'd the system shouldn't leak if it's used correctly.

When I stuck my gauges on my 6 year old MR2 it still had the same amount of gas in it as the day I bought it, all because I kept using it.

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That's the thing Crusty, use it or lose it :lol:

The vast majority don't and only think it can be used to cool the car in the summer ;)

Kingo :thumbsup:

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Kingo, while you're here do you have any idea how much a cabin filter will cost me for my avensis?

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The HP line from the condenser at the front, to the bulkhead at the rear has many bends; Toyota has a common fault in that some of these bends are stressed during manufacture causing leaks eventually. If the system is allowed to depressurise there is no lubricant going to the compressor and it fails.

The compressor has variable vanes and is permanently engaged, not engaging with a clutch as a lot of people think, so even if the AC is turned off the compressor will fail which is a very expensive repair.

I fortunately noticed the leak and had the pipe replaced but the so called AC expert who previously recharged my system did not notice the leak adding to my cost. The pipe is approx €200 plus fitting. Not all AC experts are experts if you know what I mean.

So have it checked regularly at least for leaks, if it stops working worry.

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Nice thread. I just leave mine....on. Vary the cabin temperature once in a while and thats about it. Good question from 'clangnuts'. In cold weather is the cooling part still working at all, or should I have 30 mins with a/c set at coolest?

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Nice thread. I just leave mine....on. Vary the cabin temperature once in a while and thats about it. Good question from 'clangnuts'. In cold weather is the cooling part still working at all, or should I have 30 mins with a/c set at coolest?

I read somewhere, that you can turn the AC on and the heating at the same time which is doing the same as a climate control system(it dries the air before heating it). I know if I do this with mine it clears the windscreen in seconds

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No, it doesn't heat, but as has been mentioned it's fine to leave it on while cranking up the heater knob. That way it'll nicely de-humidify the cabin air during winter. Misty windows gone in seconds!

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I came across this thread and idly followed it. Then I tried out using the a/c on the cold and frosty screen I've been having lately. What a revelation. The inside of the windscreen clears so quickly. I have obviously never thought about/understood the term "conditioning" in a/c. It stays on most of the time now. Makes up for the poor performance of the blower. Still haven't worked out what effect the little button down by the headlamp adjuster has.

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I came across this thread and idly followed it. Then I tried out using the a/c on the cold and frosty screen I've been having lately. What a revelation. The inside of the windscreen clears so quickly. I have obviously never thought about/understood the term "conditioning" in a/c. It stays on most of the time now. Makes up for the poor performance of the blower. Still haven't worked out what effect the little button down by the headlamp adjuster has.

You're not alone. Most people think the a/c is simply there to make the cabin cooler in the summer. Many of those same people would never think of using a/c in the winter, when in fact it is just as useful then as in summer (as you've described.)

Glad you've benefited from this thread. :thumbsup:

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Great thread! A couple of queries, I took my car for a service and also got them to look at the ac as i felt it wasnt cooling as well as it used to. I was told it was otherwise fine but needed "regassing". Like most people I never thought about leaving the ac on all the time. As there is apparently no leak is it worthwhile regassing it in that case?

And also, is it better to have the ac running with the cabin air recirculation on or off?

Thanks :-)

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If you don't use it semi regularly, the gas WILL leak out because the seals dry out.

If you're finding the aircon is nowhere near as cold as it should be, a re-gassing is usually worth it, but if you use the aircon regularly it should run for a long time without regassing!

If it wasn't for the seals drying out, the aircon system would never need regassing in theory!

As for using recirculation or not, tbh it doesn't really matter.

I tend to use recirc if the outside air is bad (High pollution, being near a sewage works etc.) otherwise I use fresh.

Fresh is better if you're trying to clear condensation tho'

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The trouble with re-gassing is that the AC service guys will tell you they need to drain it to re-gass it, so that they can measure the ammount that has gone in, and charge a €100 to do it. Possibly you could answer if this is necessary crustynuggets

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I have a smelly air-con, it doesnt smell whilst its on but after i turn it off the air smells really damp and musty for a few minutes.

Any sugestions on a cure ?

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Hi Guys.

As for re-gassing, yes, car a/c systems should be fully 'vacced-out' before adding new refrigerant if you're going to do it properly. Car a/c systems use very small amounts of refrigerant gas compared to commercial / industrial systems, so getting the quantity right is crucial. Add too much and the compressor will die in no time. You can buy the top-up kits from Halfords etc where you can add refrigerant yourself, but this is a very hit-and-miss way of doing it. If it were my car I'd be doing a full vac-out and re-fill.

As for the smelly air in the cabin, the first thing to check, and the most likely cause is a dirty cabin filter. Take out the glovebox and it sits just behind there. The filter will slide straight out once the glovebox is out of the way. If it's full of dirt / clogged-up, change it and you should be all sorted and smell free! Simples! :)

Failing that, your condensate line may be blocked meaning the condensate water sits around the coil rather than drain out. If it gets trapped it can get into the cabin and go stale in no-time. Are there any damp patches in the front footwells?

Like I said, the most likely thing causing it is a blocked filter, so I'd check / change that first. :thumbsup:

Hope this helps.

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