1991 Mercedes R12 Troubleshooting

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nmwhitneyjr
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1991 Mercedes R12 Troubleshooting

Postby nmwhitneyjr » Tue Nov 07, 2017 4:46 am

Greetings all,
I recently bought a 1991 Mercedes 300D that is still running r12. Seller said the ac had been week for a couple years but he never felt the need to repair or switch over to r134a as it was a weekend driver. Compressor clutch won't engage. That tells me there's insufficient refrigerant in the system. My question is whether there is a drop-in for r12 with dye that I can put in just enough to check for leaks. Once I've identified that, I can move on to evac, repair and replacement of the r12.

Your thoughts?

Peace,
Norm in NC
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Cusser
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Re: 1991 Mercedes R12 Troubleshooting

Postby Cusser » Tue Nov 07, 2017 6:07 am

There is UV dye compatible with R-12, have some in my 1988 Mazda truck (still R-12). But one needs the correct injector for this if there's still R-12 in the system, so my mechanic did this for me.

If all the refrigerant is out, then UV dye can be simply be added, then the system evacuated and new R-12 added. Remember, R-12 is still legal to use in all the states, and still legal to purchase; might need an inexpensive 609 license to purchase, but there is definitely no shortage of R-12, actually a glut as few vehicles still use it, so not much demand. Still would be easier and cheaper overall to keep your system R-12 though.

I'm in Phoenix, still a fair amount of independent shops that service R-12, you may need to call around, or ask some vintage car club members. You may just want to gamble that your system just has a small shaft seal leak that loses an ounce or two a year, and just top off with R-12.

I can't say whether one could find a vintage R-12 can with R-12 on Ebay or something. Remember: NEVER add any sealers or refrigerant containing sealer to an R-12 system.
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bohica2xo
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Re: 1991 Mercedes R12 Troubleshooting

Postby bohica2xo » Tue Nov 07, 2017 12:03 pm

If you search the popular auction site for "R12 oil charge leak detector" you will find vintage cans that have some R12, oil & dye. Around 35 bucks shipped for 12 ounces.

Depending on how low your system is, that may be enough to get it to short cycle for testing & to spread the dye.

A little extra oil in that 10PA15C compressor is a good plan if it has been leaking anyway.

If you go with a vintage can, a side tap is a good investment.
Dougflas
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Re: 1991 Mercedes R12 Troubleshooting

Postby Dougflas » Tue Nov 07, 2017 5:36 pm

I have some R12 in small cans that also contains dye.
nmwhitneyjr
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Joined: Tue Nov 07, 2017 4:38 am

Re: 1991 Mercedes R12 Troubleshooting

Postby nmwhitneyjr » Wed Nov 08, 2017 12:16 pm

My thanks for your replies...

I definitely want to stay with the r12 for now... less hassle, less expensive, less work, etc. That's assuming I can run down the source of the leak.

And no, I would not put any stop leak product in any of my cars... that's like using proto-matter in your Genesis Device.

Lot's of side taps on Amazon. The reviews are all over the map. Any particular brand tend to be better than others?

I'm very familiar with r134 systems... I have a set of gauges and a vacuum pump. I'm going to need a charge hose to hook to the side tap and the low side of the ac. Again, looking for suggestions on a decent one?

Peace,
Norm
Dougflas
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Re: 1991 Mercedes R12 Troubleshooting

Postby Dougflas » Wed Nov 08, 2017 12:38 pm

I did not read where it was suggested to add stop leak. Dye is "colored oil". Check your evaporator carefully for leaks. A good place is to check the drain hose with a sniffer. Also, place a shower cap around the front of the compressor and place the sniffer into the shower cap after sitting over night. And yes, keep this system R12 if at all possible.
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bohica2xo
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Re: 1991 Mercedes R12 Troubleshooting

Postby bohica2xo » Wed Nov 08, 2017 8:53 pm

Side tap from the site sponsor:

http://www.ackits.com/85530-3-in-1-side-mount-can-tap-us-standard-31770

That tap has BOTH R12 & 134a fittings on it.

.
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Cusser
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Re: 1991 Mercedes R12 Troubleshooting

Postby Cusser » Thu Nov 09, 2017 7:27 am

Dougflas wrote: place a shower cap around the front of the compressor and place the sniffer into the shower cap after sitting over night. And yes, keep this system R12 if at all possible.


Great idea !!!

Correct - never add any sealers or refrigerant with sealers.

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