Hey all, I wanted to recharge my a/c in the w124 but I don't know which freon I already have in the system.. The past owner said he converted it, but when I got a R-13 refill can the nozzle doesn't fit on the cap, it's too big, but the cap looks new..

Did he put the wrong cap in the wrong place? or what kind of nozzle do I need? There is no sticker that says it's been retrofitted, just the factory sticker stating it uses R-12..

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78 Datsun 280Z
86 Peugeot 505
01 Subaru Outback

“Owning a car is like owning a dog. Every now and then, it craps on the carpet — but it’s still your dog.” - Jeremy Clarkson