Vehicle Air Conditioning - Regas, Top Up And Leaks.

Technically there shouldn't be such a thing as a "regas" or "top up"....as this practice was always wrong and hasn't been legal snce 2007.within the EU.
By law the system requires a certified professional to deem the refrigeration systems as gas tight.
Only an Fgas certified person can access a refrigerant system containing HFC or CFC refrigerants.
The law on purchasing refrigerants isn't being policed on Internet and I see that some outlets still sell gas to the public.

Your car doesn't use up refrigerant, but instead it becomes lost to atmosphere though leaks.
Your system has at least two access ports, many o-rings, a filter/dryer and most importantly a seal at the belt drive.
The seal at the belt drive needs to be kept from drying out, hence the advice to use the ac once a month, even during winter,; useful for clearing mist/fogging from your windscreen.
Common causes for refrigerant losses and rpairs are;
Accident or stone chip damage to the condenser coil (replace).
Leaking main bearing seal (exchange replacement of compressor).
O-ring failure (replace).
Fractured fixed pipe (repair or replace)
Deterioration of flexible hose.(replace)
A decent/competent mobile tech will charge circa £200-300 for a full test, repair, pressure test and vacuum labour.
Materials/refrigerant/oil/dye and vat extra.

View attachment 164112
If you are paying less, expect to be repeating your "regas" at least once a season, for the life of the vehicle.
Further do not look a child in the eye and say "you've done your bit for the environment", as you haven't.
1kg of R134a lost to atmosphere is equivalent to 1.43 tons of CO2, but at least it doesn't give polar bears sun burn.

Common refrigerants in uk cars are
R12 for older pre 1995 cars
R134a Most cars
R1234yf for recent cars, 2017 onwards by law and some early adopters.
The most recent is the most expensive, twice that of the older refrigerant.
However compared to FINDING THE LEAK and REPAIRING it, the cost is insignificant.
It would be like worrying about what brand of oil or brake fluid your garage is going to use.

Spanner operators will say things like "they all loose gas", "annual top ups keep the system fresh" or "it's not worth investigation, I'll drop in some leak sealer".
The bought a machine for £5k-10k and know how to connect two hoses and press a button.
You could train a monkey (tyre fitter) to do this and some garages have.

Remember if they fixed a leak, that machine would never pay for itself!.... where's the repeat business?

Sadly most people will ignore or try to debunk this;
our species is doomed.....



Ps
I can't sleep.......I was hoping that answering this would send me to sleep....
Sadly I've probably lost the audience

It's written under the bonnet, normally on the front cross member .....
E.g.
R134a 830g RHD (870g LHD)


But you don't need to worry about that ......

What I find truly amazing is the wholesale price of refrigerant and what people are pay for a "regas"....
£100+vat PER Kg R1234yf
£25+vat per Kg R134a...... updated prices from Simon's post.
Most cars take from 400g to 1000g,
OFN test gas is £28 per bottle .... at least 20 cars worth.
Machines are £5k to 10K
Spanner monkey £20/ hour?
Where's the money in it?

Due to the refrigeration cycle laws your AC actually gets colder as it runs low on refrigerant. .... most people don't realise it's not working properly until it's nearly out of gas. The only way to tell if it is still correctly charged is measuring the pressures together with air on and air off temperatures.

Each manufacturer will give advice, but generally you'll want the evaporator temperature to be between 8 and 12°C to give cooling to 18°C, too low and you'll get ice, too high and you won't get enough cooling to combat that thermonuclear fireball in the sky.

A system low of refrigerant will appear very cold close to the vent, but you'll still be hot in the car. Water (from melting ice) may start to appear in the front footwells (and rear if you'e got posh ac).


Dare I mention batteries? ... nah

 

I agree.
The only time I've had to recharge is upon supply of a new vehicle or pipe damage.

I'm not a legal person, but I believe they are breaking the law by selling these.
These are disposable cylinders and therefore banned under the July 2007 EU regulations. They have put a deposit on them to make them look otherwise.... a total con.
Further it shouldn't be possible for the public to buy CFC or HFC refrigerant without a copy of their Fgas license on file with the supplier.

The main training body in the South, "Ellis" thinks Halfords shouldn't be selling and can't see why trading standards or the environment agency hasn't prosecuted.

See
https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:161:0001:0011:EN:PDF

 

NO....
It's a good one and it helps the environment.

and Keeps my fees high

 

Wow that would have been expensive.....
You've got to strip the whole dash apart to get to the evaporator!

 

Agreed that in bulk 40Kg is around £1000 plus vat and delivery, with a monthly rental on the bottle.
However I'm not aware of any portable machine that can take that size cylinder, so it will need decanting into smaller machine sized bottles. This requires skilled labour time.

You've made no allowance for the recovery of his diesel, vehicle running, certification, licencing, waste transfer, insurance, capital costs for machine / tooling, pressure test media and the plethora of other costs.
I doubt he could afford a weekend in Clacton on the annual profits.

Secondly did he find the leak? There is no permitted leak level, so where did the refigerant go?
The only wear would be to the front end bearing and seal, so this would need replacing, if that was the cause of the refigerant loss or it wouldn't pass a tightness test..
All other seals do not wear, they are either good or failed.

Ps.
A vacuum test does not exist, just a procedure.
Failure to hold a vacuum indicates water (or water vapor) present and the procedure needs to be repeated/extended.
Typical values are hold vacuum to 0.6mTorr for 20 minutes, seal and isolate external vacuum pump, ensure system pressure doesn't rise above 3 mTorr for 60 minutes.
It has nothing to do with leak testing.
Since you cannot isolate high and low sides on a vehicle for the purposes of a pressure test the whole system is tested at 7 Barg (for R134a).
If a vacuum test existed it would effectively be a -1 Barg test!....

 

A domestic fridge or freezer is typically hermetically sealed, where a vehicle is not.
A vehicle has many mechanical joints in the system and it tends to jump around a lot. This together with heat cycling and exposure to salt, solvents and other chemicals makes for a hostile environment. The compressor has an open end for the shafts and that bearing/seal set is a weakness. Regular running of the ac, say every month is really good advice on the older clutch systems. Top tip start the car with ac switched ON and never switch the ac on while at high revs.
The compressor is ac heavy load and the compressor clutch has a hard enough job without excessive revs.
Newer cars have "always on" compressors with variable load pumps.... very clever.
Electric or hybrid cars have electric ac pumps.
Running a load of oil around the system (by operating the ac mode) helps keep the o-rings lubricated.

 

Simon, I buy gas from them and the bottles do need to be returned or they'd be illegal (july 2007 regulations).
Note the shipping costs are higher than website shows when you select uk..... they call you.

I use the mini kits myself as they allow me to take them up ladders, without getting tangled up in long and wasteful hoses.

Note refigerant is even cheaper if you buy from China.
In my response earlier I acknowledged that prices had dropped snce my original post.
Note refigeration prices have been very volatile over the last 24 months,


You can get dynamic leaks.... due to pipe movement caused the vehicle moving or just the gas/vapor cycle.
So long as you've got a shot of dye in there you can find it with a good UV lamp after a weeks driving.
It's the easiest way to see a main bearing/seal leak.