240d W123 leaking R 12 - PeachParts Mercedes-Benz Forum

stephenc1984 · #1 05-17-2018, 07:35 AM

My 240D leaks a 12-14oz can of R12 in 4-6 months. When the system is charged, it blows some pretty cold air (38-40F). I charged the system with an A/C acceptable red dye/ sealant. Apparently it is supposed to seal small leaks and if it is too big the dye leaks out so the leak can be seen. No dye under the hood, yet the system has discharged. I assume the leak is inside the cab. I cant pay someone to work on my r 12 system unless it is converted to 134a. Should I try to find the leak or just convert it to 134? What is a ball park figure to convert the system given that all the components are working but has a small leak? Thanks, Steve.

tangofox007 · #2 05-17-2018, 04:06 PM

Quote:

Originally Posted by stephenc1984

What is a ball park figure to convert the system given that all the components are working but has a small leak?

R-12 works. R-134a doesn't. Buy or borrow a leak detector and find/fix you leak.

ROLLGUY · #3 05-17-2018, 07:41 PM

Chances are you either have leaky compressor seals (very common), leaky hoses, or both. I am biased, but it would be best if you replaced most of the system, and do a Sanden retrofit. R12 is getting hard to find and expensive, so it is not worth charging a leaky system every season (or worse yet every few months). Either way you should find and fix the leaks, and find a shop that will work with you and your R12. If you would like to drive up to Hesperia, I could help you with either repairing your existing system or doing a Sanden retrofit. Thanks, Rich

ROLLGUY · #4 05-17-2018, 08:52 PM

Also, know that the R4 has no oil sump. Every time it leaks refrigerant, it leaks oil along with it. If you have been adding refrigerant and not oil as well, be prepared to replace your compressor soon. Be aware that some oils react differently with R12 and 134a. Your original system was charged with R12 and most likely mineral oil. When someone changes to 134a (I know you are still running R12), and does not flush the system, the oils are not compatible with each other or the different refrigerant. Many DIY'ers change to 134a, and don't flush, or bother to add oil. The problem, even with adding oil, is no one knows how much oil is in the system. After finding and repairing leaks, or replacing components, it is always best to flush the remaining system components and start over. As far as hoses go, it is and has been my opinion that when doing major A/C work (compressor replacement or more), ALL the rubber hoses should be replaced. There is one hose (liquid line) that is made of some sort of bomb proof material that never needs replacing. With all new components (hoses, compressor, drier, TXV, condenser), one can expect may years of trouble free cooling......Rich

stephenc1984 · #5 05-18-2018, 05:06 AM

I have charged the system with R12 compatible oil one time in the last two charges. Thank you Rollguy for the offer. I don't mind taking and paying for an A/C guy to fix it. What should the ballpark cost be to fix leak and convert to 134? Thanks!

ROLLGUY · #6 05-18-2018, 10:01 AM

Quote:

Originally Posted by stephenc1984

I have charged the system with R12 compatible oil one time in the last two charges. Thank you Rollguy for the offer. I don't mind taking and paying for an A/C guy to fix it. What should the ballpark cost be to fix leak and convert to 134? Thanks!

If it were mine, I wouldn't convert to 134a without going to a Parallel Flow condenser and fan upgrade, as well as replacing all the hoses. The 134a molecules are smaller than R12, so leaking hoses with R12 will surely leak more with 134a. And again if it were mine, I would do a Sanden upgrade as well. I feel the R4 is not worth the investment in time or $. Even if you changed the hoses and Orings, flushed the evaporator and replaced the condenser, the existing R4 would probably not last much longer. Replacing the R4 with a new or reman is also akin to a crap shoot. You won't know if you get a good one or not until you have invested time and $ into the system. At least that was my experience years ago. That is why I developed the Sanden retrofit. I got so fed up with the R4 and it's inherent design flaws (no oil sump, marginal sealing washer design etc).........Rich

BillGrissom · #7 05-19-2018, 12:00 AM

Consider that R134A is going away. I use Duracool hydrocarbon refrigerant, but not pushing it on others since many non-technical people make absurd claims about it being dangerous. HC's are a direct swap, i.e. can work w/ your existing mineral oil.

I would never use stop leaks since all of the ones I know of work by putting aggressive solvents in your system which are supposed to swell old rubber O-rings so they seal better. I imagine other things like hoses swell and degrade as well. It isn't terribly hard to change all the O-rings (use HBNR), except the shaft seal on the compressor.

stephenc1984 · #8 05-19-2018, 06:33 AM

I am pretty mechanical and don't shy away from most mechanical problems. Between A/C systems and automatic transmissions, it's vu du magic. I don't have the bandwidth to learn new systems and their intricacies. I might just keep charging it with a can of R12 every year until it gets worse.

funola · #9 05-19-2018, 12:16 PM

Quote:

Originally Posted by stephenc1984

I am pretty mechanical and don't shy away from most mechanical problems. Between A/C systems and automatic transmissions, it's vu du magic. I don't have the bandwidth to learn new systems and their intricacies. I might just keep charging it with a can of R12 every year until it gets worse.

That's a good strategy if you have a big and cheap supply of R12. If not, try to find and fix the leak. The chance of bad hoses is small from my experience of testing many old W123 hoses. If original, chances are high one or more of the o-rings in the bead lock fittings are not sealing 100%. This is from personal experience taking apart all the fittings in my 85 inspecting/ replacing all the o-rings. One of the o-rings near the turbo/ alternator (where it's the hottest) was flattened/ deformed. Start by looking for signs of oil/ wetness at the fittings and the compressor. They should be totally dry.

stephenc1984 · #10 05-20-2018, 04:41 AM

Thanks I appreciate it.