Confused by types of AC Gas
 

For starters, I didn't even know there where different types of gases so this is all a bit of learning curve for me.

I've been having problems with the AC on my C30, basically not working, not blowing cold air. I suspect the compressor but I want a proper diagnosis first.

I went to a mechanic and his first words were 'sorry, can't do anything for you' because he can't mix gases so he couldn't empty/recharge the system. Fair enough, I don't know what machine he has but I understand now that it's illegal to mix gasses, so I have no problem with that nor him.

On the last recharge (the AC didn't work before then either btw) the garage recharged the system with something called 'Duracool 12a'. From my reading, this is an 'eco' substitute for R12 and R134a.

What would be the 'correct' gas for my 2009 C30? And can a Kwik-Fit like place (that does R134a) do a decent diagnosis on my non-functioning AC?

The correct gas should be on a label on one of the ac system components or labels under the bonnet and often in the owner's manual.
In the UK, places like Kwik-Fit test the system for leaks prior to evacuating and refilling as filling a leaking system is illegal.
If they find a leak, they can't fill and don't charge so you get a basic system check for free.

I doubt other countries will be much different but ask the individual garage for clarification.

As technology and environmental concerns have evolved, gases have changed - however not that often.

The first gas commonly used was known as R12 but this was phased out in the mid 1990's and replaced with R134a. R134a has continued to be used in 99.9% of cars until fairly recently (2018-ish) when manufacturers started to move to R1234YF which is broadly the same but breaks down more easily in the atmosphere. It's also circa x3 the cost....

But any C30 will be R134a which is still commonly available. Kwik Fit is likely your best first step as if there is a leak, or they fill the system and it doesn't work - they don't charge.

I'm now wondering why a system that had R134a in it could be recharged with R12 but it now seemingly can't be done back to R134a.

it has been illegal to use R12 for the last 25 years or so , you really should take it to an AC Specialist , or Volvo dealer ... If you have to keep having it filled you have a leak , It should be leak tested , Favourite place to leak is the condenser.
The different gasses have different connectors so it should not be possible to put the wrong gas in . Take it to a trusted expert !

It's an R12 substitute (Duracool 12a) rather than R12 itself that's in the car at the moment. Whether that has the same illegal components, I don't know. It's certainly still available and sold in canisters and the like on ebay, amazon, etc. so I'm guessing not.

Whether it's a substitute or whatever - it's the wrong gas - your car needs R134a.

Even if it has been filled with the wrong gas, providing there's no damage to the internals it can still be refilled with the correct gas. Garages equipped with the correct system to do the work will put the system under a 99% vacuum and hold it for 20 minutes. This is a basic indicator if there are any major leaks, and any old oil or moisture will boil off and be removed, ready for the new gas and lubrication.

If the garage doesn't have the machine to do this - walk away... they're probably not legal either.

Assuming that the system doesn't leak and is successfully charged with the correct amount of R134a, and the A/C still doesn't work then your best bet is a dealer or independent with Volvo diagnostics. There are some basic readings that can be taken from the A/C system and it's possible to operate the compressor clutch manually - this will help diagnose the real problem - if you can find a good car A/C specialist - that might be a good try as well.

If the system does leak - on those cars it's usually the condenser at the front that fails, it's a relatively easy job to change it. Again if it does leak, a garage with the correct equipment will likely find it either by using a "sniffer" or adding a dye to the system which shows under UV light.

That’s what I was going to put but frankly you put it better than o could!

And yes, R134 has been used for decades.

Just done a quick Google and apparently "Duracool 12A" is supposed to be able to replace R12 and R134.

But as is often the case, especially with Volvo, stick with what the manufacturer specifies...

Unless you take a car in that definitely uses 134a, but they make up some BS about "It using older gas that we can't supply" when they're presumably too busy/ clueless to find the filler valve thing.