HELP, inadvertently added r134 to an r12 system - PeachParts Mercedes-Benz Forum

locry · #1 07-30-2006, 08:13 AM

HELP!

about 3 weeks ago, a friend left me his 124 300TD, which i eventually bought from him. The car was low on freon then so i went to an AC shop to have it refilled with r12 since it was an 87 model. But just to make sure i called him up and asked him if he had it converted to r134 as is required here in the Philippines. He said that yes it had been converted but was not a hundred precent sure... but he did have it charged with r134 before, that he was sure of. Anyway, to make a long story short, i had it charged with r134... 3 weeks later the system loses freon again... so i asked him to dig up his old receipts to check what freon the car really used... lo and behold... R12!!!

what should i do now? can the system be saved by evacuating the system and recharging with r12 and loading up with appropriate oil? or is my system toast?

POS · #2 07-30-2006, 08:33 AM

Your system will only clog with the wrong refrigerant/oil. You need to flush it with a vacuum pump and some AC flush, then put it back together. Are you certain you solved the leak in the first place?

locry · #3 07-30-2006, 09:11 AM

i'm not sure if the leak has been found and solved, we did find that the expansion valve fitting had a minor leak, which was solved by tightening the nut, that was 3 weeks ago... today i had it recharged again with r134... its blowing cool air so i'm hoping it didn't clog the system... so i still have a leak somewhere...

any tips on how to search for the leak... without using dye, coz its hard to come by... can i just have the evaporator pressure tested in-car?

anyways... my first order of business is flushing the system... what's the proper way of doing it? does the compressor have to be off the car?

locry · #4 07-30-2006, 10:22 AM

Or can i just have the shop recover the 134 and have it topped of with r12 again? Did the 134 contaminate the oil that was in my system?

Johnt49 · #5 07-30-2006, 11:22 AM

No need to worry. The short amount of time the 134a was in there won't hurt anything. While the system is empty it would be a good idea to replace your schrader valves. After that evacuate (vacuum pump) the system for at least 1 hr, this will remove any moisture & residual 134a gas from the system, then close both valves on the gauge set, shut off pump & observe vacuum on low side gauge. It should hold vacuum. If the gauge starts to move toward "0" you've got a leak. Don't waste any valuable R12, recharge with 134a & leak check it with a leak detector. Once you find the leak, purge the 134a from the system.

sixto · #6 07-30-2006, 03:57 PM

I don't believe there is a law anywhere in the world that requires R12 in a functioning system to be removed. At most it's illegal to sell R12 (not in the US) so there's no practical way to recharge a system. There is so much misinformation about R12 and AC shops use this to their advantage.

AC systems that originally had R12 are operating at the margin at this age. I would not compromise that further by converting to R134a especially in Manila. Plus I find it hard to believe that there is any serious enforcement of environmental laws at the consumer level in the Philippines. Just about every imported car is running in open loop after they discard the oxygen sensor. That's a more serious problem than a dozen cars still running R12.

If you're going to live with recharging your system every couple of months then by all means do a proper conversion to R134a. If you're serious about fixing the leak (tightening the expansion valve is not a serious fix because it did not come loose on its own) then I'm sure you'll be able to find R12 and someone to charge your system with it. Worst case is you buy a 70s car with working AC, reclaim the AC for your MB, refill the 70s car with R134a and sell it.

Sixto