Air Con regas

[AlistairMcD]

Had the car in with a main dealer for a service. All good except they say I need the air con gas sorted. They checked the system and all is good - just need gas. They kindly offered to do this at £220 + VAT and I declined (for now after some further advice)

My question is - what are peoples thoughts on these DIY kits available from the likes of Halfords. Any videos I watch and it looks really easy. However, I feel that it could be screwed up quicker than a Liz Truss budget.

[ian448]

The diy kits are ok but by the time you’ve bought the canister and the adapter your probably looking at around £65 . The same as what a garage will charge to regass it

[thebraketester]

Don’t use those things.. Just Google for a local air con person. Chap local to me does it for 50quid.

[Simpo Two]

thebraketester said:

Don’t use those things.. Just Google for a local air con person. Chap local to me does it for 50quid.

+1. The good thing is that you know the rest of the system is good (so it won't leak out in 3 days like it usually does)

[cletracboy]

When done properly the system is vacuumed out and moisture removed, the gas is weighed and the correct amount of gas and oil pumped back in. A more thorough process than diy option, but £220 seems expensive.

[funboxster]

My local AM dealer wanted £250 + vat for a regas. I said no thank you! They probably sub it out and take a margin cut. Most places, Kwik fit, Halfords, etc will do it for £100 ish.

[PurpleTurtle]

My local mobile guy far less than that for a full system service incl weighing gas and topping up to exact amount. He works across all premium brands.

I feel your being asked to pay a massive AM tax there, when you’ll probably get a better service from an AC specialist.

[CAPP0]

DIY kits are generally regarded as a no-no unless it's a very minor top up. Every car has a set weight of gas required and the DIY kits don't measure that.

I had my DB9 done (thoroughly and properly, I watched) at a local independent place last year for £65. Included a full vacuum test for leaks (and the vacuum also ensures that the correct full amount goes back in).

£220 is nothing more or less than simply AM tax being applied.

[bogie]

Last time I had mine done a couple of years back at the local garage that does my tyres, MOT etc, it was £75. Theres nothing fancy about AM aircon system.

[BGB autosport]

Worth checking groupon, I had my past audi done for 35 quid at ATS euromaster.

[pschlute]

bogie said:

Last time I had mine done a couple of years back at the local garage that does my tyres, MOT etc, it was £75. Theres nothing fancy about AM aircon system.

Are you sure ? I seem to remember that AM aircon gas is breathed out by virgins on the slopes of the Himalayas

[Simpo Two]

cletracboy said:

When done properly the system is vacuumed out and moisture removed, the gas is weighed and the correct amount of gas and oil pumped back in. A more thorough process than diy option, but £220 seems expensive.

I don't understand why/how it's done by weight. How do you weigh gas? Wouldn't a certain pressure achieve the same thing and be much easier?

[thebraketester]

Simpo Two said:

I don't understand why/how it's done by weight. How do you weigh gas? Wouldn't a certain pressure achieve the same thing and be much easier?

Put the bottle on some scales and tare it and keep an eye on the weight loss as it's been dispensed. That's how the old school people will do it.

[CAPP0]

pschlute said:

bogie said:

Last time I had mine done a couple of years back at the local garage that does my tyres, MOT etc, it was £75. Theres nothing fancy about AM aircon system.

Are you sure ? I seem to remember that AM aircon gas is breathed out by virgins on the slopes of the Himalayas

My local garage uses aircon gas breathed out by virgins on the slopes of the Himalayas, but they're not wearing AM overalls.

[Simpo Two]

thebraketester said:

Put the bottle on some scales and tare it and keep an eye on the weight loss as it's been dispensed. That's how the old school people will do it.

So weighing a liquid I presume. But I still don't see why pressure isn't adequate. If you have a flat tyre you don't weigh the air, you just pump it up to a pressure...

[F1NDW]

Simpo Two said:

So weighing a liquid I presume. But I still don't see why pressure isn't adequate. If you have a flat tyre you don't weigh the air, you just pump it up to a pressure...

Simpo there is far more involved than just pumping a tyre up with air. Have a quick look for a youtube video about A/C and you will see why the weight of liquid/gas in the system is important. If it was that easy then just buying the top up bottle would be the simple answer. It can be done with the top up bottles but you do need to know what you are doing so that you can also get the suction and discharge pressures in the system correct. To do that you then need a set of fridge gauges and cost are already starting to rise.

[LTP]

Simpo Two said:

So weighing a liquid I presume. But I still don't see why pressure isn't adequate. If you have a flat tyre you don't weigh the air, you just pump it up to a pressure...

Long story short. The refrigerant in a running HVAC system exists in two states; both liquid and gas, and has two different pressures at different points around it, as it operates with a "low pressure" and a "high pressure" side. The system works by using the latent heat of vaporisation (the reason wet hands feel cold in a breeze) to extract heat from the cabin and dump it out of the condenser radiator at the front. I believe you can charge it using pressures, but you have to know what you're doing, and measure the pressures at two points with the system running and stable, especially as I believe modern systems have built-in electronic feedback loops that tweak the expansion valve settings and change the pressures, depending on the temperature at the evaporator.

In your tyres you just want a static pressure to counteract the weight of the car (although you check them when cold, as the pressures will increase as the tyres warm up). In an HVAC system you're trying to use a known quantity (mass) of refrigerant so the system operates at the design temperatures and pressures. Have a watch of this.

https://www.youtube.com/watch?v=NSUeRlJ2P0g

[8Tech]

Re-gassing is probably an unfortunate way of describing it, but it is the usual way. The "gas" is in liquid form in the system due to the pressure and so the refrigerant in the system (the gas) can, and should, be correctly weighed. Also in the system will be PAG oil (PolyAlkyleneGlycol,) that lubricates the seals and the compressor, and UV dye that will show-up any leaks should they occur.

If your car uses the "older" R134a refrigerant, then the prices quoted previously will be about right, £50 to £100 being appropriate.

When I say "older" refrigerant, it is the middle age as the "old" refrigerant was R12 and that is now banned since 1995, however, if your car is very late, then you could have the silly expensive R1234yf, and you may well find the quickfix establishments are more expensive, and you would be advised to use an AC specialist.

[embdenb]

The modern method for “regassing” a AC system is far different from the old sight glass or refrigerant weight method.
A modern system consists of hooking up the high and low sides of the vehicles system to a machine. The vehicles make and year is entered into the devices panel and that’s it.
The device extracts any refrigerant in the system, checks for leaks. Applies a vacuum and charges the system with the correct amount of refrigerant.
There is virtually no labor involved and the correct charge is applied consistently every time.

[alabbasi]

AlistairMcD said:

Had the car in with a main dealer for a service. All good except they say I need the air con gas sorted. They checked the system and all is good - just need gas. They kindly offered to do this at £220 + VAT and I declined (for now after some further advice)

My question is - what are peoples thoughts on these DIY kits available from the likes of Halfords. Any videos I watch and it looks really easy. However, I feel that it could be screwed up quicker than a Liz Truss budget.

So many things wrong here:

1) Air conditioners are a sealed system. If it needs gas, it means that the gas has leaked which means that you have a leak
2) If you don't know about air conditioners, leave it to the experts. Unless you have gauges and a vacuum pump, you're not going to do your own work
3) Pay the £220 + VAT and stop listening to advice from anyone who tells you to get a kit from Halfords. The cans are fine, unless they have leak sealer which is bad stuff. Without a proper gauge set and a vacuum pump, you'll be doing it wrong and that's what will mess your system up

Nothing wrong with DIY, but you own an Aston Martin which is an expensive car to repair if you screw it up. If you don't like their prices, find an A/C specialist and have them do the work