Can anyone tell me if adding R134 to top up a R12 A/C system would work or would it cause damage. I am told that R12 is illegal in Canada because it damages the ozone layer. Is it still allowed in the USA?

I dont think they are compatible. first, valves dont match! Second, if you have r-12, evacuate 134 and change valves to accept r12. Better with accomplished mechanic. good luck Abe G

Absolutely not. That's a disaster waiting to happen.

Its a definite no no. Completely different valves and fittings needed in your system for a start. Dont even think about it they dont mix.

I very much doubt R12 is illegal but the point is that no more is being manufactured worldwide since its disposal is damaging to the environment. The existing stock is still circulating and able to be used. R12 seems to be much more effective than R134 so if you need a small top up then try and find some more. If you do decide to convert then make sure someone pays you for the R12 they take from your system as it is a valuable commodity.

Keith

As Abe pointed out, the fittings are different. You won't be able to charge the system.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Not only that you need the correct fittings to charge the system but you also have to use the correct oil. I have heard from people with great sucess using the R134 conversion kit from the auto-part stores. However, I recommend keeping the R12 system if all you need is a top off.
Good Luck

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1991 420SEL Project Car (Completed and rides beautifully) http://www.peachparts.com/shopforum/showthread.php?t=112321
2000 BMW 740IL
2000 Integra Type R - Track Car - SOLD
2005 S2000 - Track Car
06 C230 Sport
89 560SL

Many people here know that I am not a fan of converting R12 systems to 134, but adding 134 to an R12 system is a disaster waiting to happen. If there is enough 134 in the system, the oil will not circulate.

I doubt that 12 is totally illegal in Canada, only controlled. With the mild climate in most of Canada I doubt that it is much of a problem.

Good luck,

R12 is illegal in Canada. You cannot repair existing R12 systems. They must be converted to R134 if you are to repair your system. R12 is not available for purchase.

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John Shellenberg
1998 C230 "Black Betty" 240K

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