Resolving A/C Leak 260E - PeachParts Mercedes-Benz Forum

ps2cho · #1 09-20-2009, 12:27 PM

Alrighty...today is my A/C fix day. I plan to go with a propane route so I don't spend inordinate amounts of money with R134a for it only to leak out again.

I bought an A/C pressure gauge set and it held pressure for several hours....I topped it up with R134a and after about 2 weeks it leaks out.

If it is holding a vacuum it shouldn't leak out should it?

Any ideas? I also think propane will help me figure out where it is leaking too.

Matt L · #2 09-20-2009, 12:45 PM

Leaky system, propane, sounds like a recipe for success! A flick of the Bic (R) will help you find the leak.

Seriously, it will be easier to find the leak with a refrigerant in the system and an electronic leak detector. A shop can probably do this for a minimal fee.

And no, the ability to hold a vacuum does not mean that the system is tight. The converse is true though; if you don't hold a vacuum, you will never hold pressure.

mramay · #3 09-20-2009, 02:02 PM

I have two 1987 W126's, a 560SEL and a 560SEC, both of which had AC problems. Once the refrigerant was out of the SEC's system (it's fault, not mine), I disassembled every AC connection and put in new o-rings. That made a big difference!! The SEC had two o-rings in the compressor split, one pinched in a high pressure line, one fitting with two (2) o-rings in it, and several more just plain hard o-rings. Now I understand why it couldn't hold pressure!!

Went to AutoZone for their box of miscellaneous AC o-rings (green, viton), which was about $25. I use silicone grease as a neutral lubricant on all o-rings so they don't get damaged during reassembly. The SEC held 23" hg for an hour and I put in a little isobutane and the rest was propane. Freeze your buns off here in Vegas.

The SEL AC didn't work when I bought it in '03, but four new o-rings in the top of the compressor and two more in the freon line connector fixed it - maybe $5.00 worth of parts. I didn't know then I could use propane so I had it converted R134. It's six years later and every year or two I add a little R134 to the system to get it cold again at the start of summer. This winter that car is going to be returned to an R12 set of fill connections and then the isobutane/propane mixture. It's time to replace every o-ring I can get to as well.

Matt L · #4 09-20-2009, 04:57 PM

Quote:

Originally Posted by mramay

This winter that car is going to be returned to an R12 set of fill connections and then the isobutane/propane mixture. It's time to replace every o-ring I can get to as well.

To remain legal, leave the 134a connections in place.

ps2cho · #5 09-20-2009, 10:19 PM

I think I may have figured it out....I saw some bubbling at the low side port, so I swapped it with a new connector and the bubbling stopped.

but now the compressor won't kick in. I filled up with 35oz and system reads 110psi which should be more than enough to kick the compressor in.

I swapped the klimate relay out of my wagon as I know it works and still no luck.

How do I hotwire the pressure switch?

ps2cho · #6 09-21-2009, 01:33 PM

Forgot to mention I am using Enviro-safe 12a as refrigerant. I used 2 cans. It says each 6oz can is equivalent to 18oz R12.