Re-filling Air Conditioning

[Fran]

Just a bit of advice from those more knowledgable than me please!

The garage has just called to say that my air-conditioning unit is due for re-filling and that it should be done every two years. 

I never heard about this before (certainly not two years ago when they claim it should have been done previously) and wonder if its just another fundraising effort on behalf of the garage (cos I knocked them down on the price of the service)?

Anyone know if it does needs doing, or the consequences of not doing it?  Presumably the air-con will simply stop working if it really needs re-filling?

Thanks for your advice.

Fran

P.S.  Its a Toyota Corrolla approx 5 years old if thats of any relevance.

[Steve Pyro]

Fran, the AC system compressor clutch is cycled via a pressure switch in the gas circuit.  I've you've had a loss of gas due to a leak through seals etc, the pressure switch will open circuit and not allow the AC to function.  Basically, if you've had a loss of gas, it won't work.

The system pressure (and hence, gas charge in kilogrammes) can be checked by temporarily fitting a pressure gauge to the circuit pipework (this also doubles as a filling valve should the system need to be topped up with gas).

Loss of gas can result from shaft seals in the compressor hardening with age, impact damage to the condensor or loose pipe fittings.  A good way of redcing the effects of shaft seal leakage is to run the car's AC for 10 minutes or so every week all year, whether you need the cooling effect or not.  AC also 'drys' the conditioned air, making it easier to clear your steamed up windscreen in winter.

I suggest you run your AC on recirc on fully cold for 15 minutes, then poke a thermometer in one of the car's interior vents.  If the temperature is pulled down to the low teens celcius (or lower), then all must be working well.

[Fran]

Umm - excellent  - thanks for that Steve - great diagram!   

So, if we get back to basic "Air-Conditioning 101":-

1.  Does it need refilling every two years as a matter of routine even if it appears to be functioning properly?

2.  Are there any nasty (or expensive) repercussions of not refilling it?

Thanks.

F

[Steve Pyro]

1. - No (assuming it's working okay)

2. - No (assuming it's working okay).  The refrigerant gas has an inbuilt lubrication function.  Assuming there have been no leaks, it should still been able to lubricate the compressor.

If you really wanted to, you could go to an independant car AC specialist for a AC pressure check.  What price has your garage quoted?

One thing that IS worth changing at 2 to 3 yearly intervals - BRAKE FLUID.

[Fran]

It just went in for routine basic small service and the two extras they highlighted as being needed were the air-con and brake fluid.

I said ok to the brake fluid - I dont mess around with brakes!

They quoted £80 + VAT for the air-con - but I said not to bother with that for now. 

I never had to re-gas my old MR2 in 10 years and it always worked fine!

F

[smokie]

IIRC filling costs around £70 in a dealer (may have gone up a bit now).

Once when I had a leak (AC, not personally!) - they wanted to re-gas with a dye in it to identify the source (£70), fix the leak (probably multiple £££s) then re-gas with proper gas. I used the "windows open" AC instead from then on.


Steve - I read somewhere that the lubrication reason to refill has reduced as manufacturing techniques are better. No idea if this is true though. And certainly not on Fran's car  

[Steve Pyro]

Old CFCs such as R12 and R22 needed an additional lubricant.  Current 'ozone friendly' gases such as R134a don't have this problem.

Fran, if the worst happens, as Smokie said, you always have the windows.

[Fran]

And certainly not on Fran's car  

Are you suggesting my old Corolla is in some way of inferior manufacturing standards?  (or that I am less prone to a gas leak than you are?   )

F

[Lorry]

Some useful advice at the right time.  Especially as the aircon hardly gets used till Le Mans - now is the time to test it.

Halfords sell cans of gas, some with pressure gauges, but you have to know which gas you've got, and if its leaked out, it'll leak out again.

I know that gas reclaim kits etc are expensive, but why do garages charge £80 for a pressure test.  if Kwikfit did that for the tyres, they'd soon go out of business

[Robbo]

I'm led to believe that the machines they use to refill your AC, reclaims whatever gas is stored on the system first then delivers the right weight of gas back into your system. You could barter with the garage by only paying for the gas that wasn't in the system to begin with!

They can also inject the system with a dye that will show up under ultra-violet light, any leaks the system may have.

[Steve Pyro]

There's a difference between maintenance for the sake of maintenance (ie. blindly accepting the word of a garage 'expert' and innocently parting with your hard earned wedge) and proper, considered planned preventative maintenance.

[Lorry]

get the car serviced, air cons need regular maintenance, which means topping off the gas, whats the point of having it if you are unwilling to look after the car properly?

With the service bill for a Ferrari, £80 for the aircon is peanuts. Is it 3 grand for a cam belt

[Fran]

check question, Fran, non-car expert or Mitsubishi trained fitter, which one has a better idea about the state of the vehicle and what needs to be done within the car maintenance schedule.

Not sure what Mitsubishi has to do with anything, but the reason I have queried it here is that I was told "its routine to re-fill every two years" - but the same garage has serviced my car for the last 5 years and has never mentioned this routine every two years before now.   

When I asked if it actually needed to be refilled he said he didnt know but its normal just to do it every two years as a matter of routine anyway.

As I said before, on my previous Toyota in the course of 10 years I was never told about it needing re-filling according to any pre-set schedule, and it continued to work perfectly.

There may or may not be qualified mechanics in CA, but I dont doubt there are many people with a lot of knowledge and experience of cars whose judgement I respect far more than a grease monkeymuch respected highly trained and fully qualified Toyota mechanic dealing with a female customer!

F

[Lorry]

I suspect that the manufacturers through a number of things like this into the service schedules to help reduce waranty claims

The aircon does need a look at every couple of years but sticking a thermometer down the vent just about does the job

[dukla]

Halfords sell cans of gas, some with pressure gauges, but you have to know which gas you've got, and if its leaked out, it'll leak out again.

Halfords will also test your pressure without charge (or it was about 12 months ago when they did mine).