A/C Changing from R12 to R134A Mulsanne S 1992

[Portamno]

Hi,

My Mulsanne S 92 is ALMOST ready to go, after 4 years of endless search for the right mechanic, here in Portugal....Now comes the issue of changing the gas on the A/C from R12 to R134....

I have searched the net, and on flying spares I have found a kit which provides 2 ounces of oil and the right plugs....HOWEVER, reading other related material it seems that the "drier" in the A/C system also needs to be replaced??

Can anyone offer a more complete description of what must be done?

THANK YOU

[keith9849]

if you look online you should find an alternative 'fluid' that will work in the ld systems without damaging seals and without changing the 'drier'. Can't remember the code-name for it, but it is a fait bit more expensive, but far cheaper than than changing seals and drier.

[Portamno]

Thank you very much for your reply!

Will look for it here in Portugal!

[keith9849]

Bear in mind that I have my tongue firmly in my cheek as I write this, BUT it seems that you can charge the old systems with with patio gas. I am not advising a novice to 'have a go', but in the States where a/c has been fitted to the humblest and crudest forms of transport for decades, and where a lot of DIY goes on, this happens.

For those who say "what if explodes?", I answer that we drive around with a full complement of fuel on board every day, pumped into the superheated confines of an engine compartment. Further, we merrily light-up out barbecues without a Fire Officer on hand, and pipe natural gas into our houses to heat the place.

If anyone has more info on this let me know. Obviously the canister has to be upside down so that liquid (rather than gas) emerges from the hose and into your cherished motor. BUT I would extinguish that fag before attempting this.

AND before anyone responds in a rude or inappropriate manner, I should tell you that I voted for BREXIT, and approve of Trump's decision to renew sanctions on Iran. Do your worst!!!!

[alabbasi]

R12 uses mineral oil and R134a uses PAG. The oils are not compatible and mineral oil won't be carried by R134a. The right way to do it is to flush the system (mainly the compressor and the condenser) then add the appropriate PAG oil before charging. If you open the system, you should change the dryer which is typically not expensive.

If you don't want to deal with that, then recover through the high side and pull a vacuum for at least a couple of hours and let the pump try to suck as much oil out as possible. Use Ester oil which is compatible with both systems.

R134a runs at a higher pressure than R12 so you'll need to charge by pressure and not volume in order to get the right amount in (usually 10-20% less).

Don't bother using propane or anything other than R134a. Whatever people say about it is idiotic because a/c systems were not designed to carry a fuel. R134a is very efficient. If it's not working effectively, it's more likely something to do with poorly performed conversion than it is a poorly performing gas.

Edited by alabbasi on Sunday 20th May 22:26

[Portamno]

Than you very much for your reply, Abbasi! Will do. My A/C mechaninc has taken the course on R 134, she should know this....But never sure of verything 100%. Will go the garage and talk to her about it,.