when I purchased my 240D, the owner said the AC has been converted to R134. How can I tell if the AC is R12 or R134?

Bob 1981 240D

Assuming it was properly converted, R-134 uses two quick disconnects usually with a blue plastic cap, and a red plastic cap. R-12 as originally equipped has schrader valves which use metal screw on caps. If you remove a cap and see what looks like a bicycle valve stem, thats R-12. If it wan't properly converted, it's a crap shoot. Chuck

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2000 C230 Kompressor "Frosty"

2007 PT Cruiser
2001 VW TDI Beetle
1999 Landrover Discovery II
1971 Corvette

Gone: 97 Cabrio, 83 240D, 93 VW Eurovan, 95 Volvo 850, 93 Chevy Astro Van, 77 VW Bus, 99 VW Jetta, 74 VW Bus

thanks, there is a blue and red cap dealing with the AC. AC works and while not supper cold, does keep the heat and humidity down here in NC. A whole lot better then driving around without any air.

does this mean, it will be cheaper to fix if anything goes wrong?

Bob 1981 240D,

Find temperature-pressure charts for both refrigerants. Compare pressures at different temperatures and see which chart you match.

While you are at it read about subcool, superheat, sensible heat and latent heat. Check out the differences between a system with an orifice and a system with an expansion valve. After all of that you will be just a little smarter and maybe a lot cooler.

Last year, when I was ignorant of most AC issues, my Benz dealer sold me a screw-on blue and a red caps that merely replaced the original brass ones. Now had I left them on, someone would say I had converted to r134 which I hadn't.

So aside from the colour of the caps, what else is done in a covert? Do they replace the hoses with different vales, etc?

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1984 300SD TURBO DIESEL