My W126 AC compressor clutch froze and snapped the belt that I just replaced 2 months ago. The pump will not turn by hand, so I am assuming the bearing is shot.I ordered a rebuilt compressor w/clutch and am going to keep it R12 (since I read that its best to keep the '86 560SEL that way) and was wondering do I need to flush the system?? I am replacing receiver/drier , expansion valve, temp sensor and pressure sensors. I understand I need to put mineral oil back in and am going to get some from www.ackits since I live here in Phoenix . Do I need to put mineral oil anywhere else? Thanks in advance for any help.

Rob

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R@Z()R

1986 560 SEL

It is almost certain that your compressor lost more than just a bearing. When the freeze up they have failed internally and scatter metal debris throughout the entire system.

In the case of compressor failure, flushing is not the word for it. You need to break EVERY connection in the system and COMPLETELY flush EVERYTHING. Flush it forward, flush it backward, then follow that up with a flush both ways. Then once you're through with that, then flush everything, and follow up with a THOROUGH flushing. Are you getting the picture here?

If you DON'T flush, and flush and flush and flush THOROUGHLY, it is almost a complete certainty that you will lose the new compressor. You also should contact your local auto a/c supply and see what they can offer in the way of a suction side filter. This is a filter that you can put inline very near the inlet to the compressor. If you can do this, you will still need to flush, but it doesn't have to be so exhaustive.

A byproduct of flushing is that you will remove all the oil from everywhere, thus you can get the correct amount back into the system. I think you will find that it calls for 6 oz. Put 2 in the evaporator, two in the condensor and two in the compressor before hooking everything back up with fresh o-rings everywhere.

Make SURE that you get ALL the flushing agent out of the system and remember that the system has been completely opened and MUST have a new r/d replaced as the last item after closing up everything else. And do a THOROUGH evacuation before charging it.

You are very wise for staying with R12.

Hope this helps,

Yes

I'd dump the R12 and go with the R134a, especially since you're replacing the compressor. Unless you spend over 75% or so of your driving in-town.

Gilly

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Larry pretty much summed the flushing up. You can't do it enough.

Gilly - did you see where he lives? Unless he gets the folks at ackits to help out installing a parallel flow condenser in there he will NEVER be happy with the 134 in that car at that climate.

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Jim

At highway speeds it'd be fine, not quite as good at intown speeds.

It's a "dry heat" .

Gilly

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Just wanted to say thanks for your recommendations and help! That's why i love this site! I borrowed a siphon sprayer from a neighbor and flushed my system over and over again. Replaced receiver/dryer, expansion valve and compressor and all new orings on all fittings that were broken. Put in some mineral oil and just had the old girl charged with R-12 and she's blowing ice cold....especially nice here in the desert!!

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R@Z()R

1986 560 SEL

Good work! I think staying with R12 in Phoenix was a good move. These systems don't have a lot of extra capacity to give up when going to 134.

Stay cool,

Can someone explain the flushing procedure in more detail? Could I do this with a mighty vac oil changer?

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David
1986 300E Anthracite + ECodes + MB Mileage Award

No.

You break EVERY connection and use a flush gun which is basically a pressurized vessel with a flushing solvent and a blow gun. You blow the solvent in both directions and blow it out with compressed air.

If you are flushing after a catastrophic compressor failure you flush back and forth multiple times to remove all metal debris. If you are flushing to remove oil to change from one refrigerant to another you don't have to be as dilligent. You must make sure that you remove ALL traces of flush, then replace r/d last.

Add the correct amount and oil type, evacuate and charge.

Have a great day,