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Old 07-12-2003, 08:43 PM
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Unhappy a/c compressor replacement

Hi everyone! Hoping to get some quick help (sorry for the short notice!) on a compressor replacement on a 1988 300E w/76,000 miles.

My friend and I are going to tackle this project tomorrow afternoon and I'd like to know of anything that I can do as a relatively non-mechanical person prior to digging into it.

Here is the background: driving down highway at 55mph, let off gas to stop at stoplight, a/c starts blowing hot air (conveniently on the hottest day of the year so far!). Take it to shop, they state that hoses are leaking around manifold. I want second opinion and friend puts gauges on and shows a full charge. Try to jump compressor pressure switch and no compressor movement, hence diagnosis of failed compressor (don't know if it's black death or not).

Have system evacuated and locate a/c shop to rebuild compressor for $250 vs. buying replacement rebuild for $500. Will replace rcvr/drier, expansion valve and have hoses rebuilt (if needed) while doing this project. This is an R-12 and intend to stay with this as we can buy at local auto shop for $22.99/can.

I've done the searches on this forum and found the info about flushing, flushing, flushing and found another about getting the serpentine belt loose to remove compressor but seems like my uncle had pointed out a "tensioner" that could be loosened to remove compressor without removing fan shroud, etc.--true or not.

Anyway, thanks in advance to anyone who can help me in this project...I'm anxious to complete it as it is today a pleasant 113 degrees!!

Thanks! Mike
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Old 07-13-2003, 09:45 AM
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Why are you replacing/rebuilding the entire compressor just because the clutch won't kick in? If you have jumped 12Volts to the compressor and it won't engage, the problem is most likely the clutch not the compressor. You can't determine if the problem is the compressor until you kick in the clutch.

Maybe I misunderstood what you said, but the above is the response to what I understood you to say.

Good luck,
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Old 07-13-2003, 10:50 AM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
I read it similarly.
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
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Old 07-17-2003, 01:01 PM
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update!'s a sorta answer to the two responses

On day we were going to tear into this, another friend came over (previous mechanic at CA BMW dealership) and between the two of them decided that they weren't exactly sure what the problem was and that I'd better take it in.

Indy removes, takes to local rebuild shop who says they can't rebuild because (paraphrasing) a valve got into the piston and "screwed the goose". That is a terrible second-hand translation of what they really said but works for now.

Bottom line is bad compressor and now looking for hopefully inexpensive replacement. Speaking of which reminds me to call Phil real quick and see what he says!

Anyway, the saga is ongoing and I will update as things move along.

Thanks again for the input! Mike
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Old 07-17-2003, 05:23 PM
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Since the compressor failed internally, you will need to do much more than simply replace the compressor. Upon compressor failure such as this, there is debris strewn throughout the system that, if not TOTALLY removed, will wreck the new compressor almost immediately.

You need to THOROUGHLY flush the system everywhere. Break apart all connections and use LOTS of flushing agent throughout everything, then flush again, then again, and after that flush it again. Then ENSURE that you have removed all flushing agent.

After flushing EVERYTHING, replace the filter drier and evacuate thoroughly before recharging with R12. These cars have marginal a/c capacity, so going to any refrigerant other than R12 would be a mistake.

Good luck,
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Old 07-24-2003, 11:33 PM
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the saga continues! :(

Okay, finally the indy got the new (rebuilt) compressor installed along with rcvr/drier and TXV. Drove home after sitting in 100*+ sun and wasn't terribly least not as much as I remember it being.

Put thermometer in center vent next day and have not seen vent temps much below 60* and certainly no lower then 55* (this can occur when i leave fan on low so air stays in contact with evaporator longer but it is too hot to drive that way) with ambient of 90-105* and some humidity but certainly no more then 50%. Also, at stoplight, temps creep up to 70* and 55-70* is not gonna cool this beast in this ungodly heat!

So, search forums, find out about monovalve, check that and seems like it is stopping the hot water but past monovalve the hose is still warm but figure that's because of the ungodly heat

Haven't yet checked the little grill (mine appears to be by my sunroof switch?) to see if air is being drawn in to fan by glove box per LarryBible...can't find a cigarette!

also, looking at sight glass during idle, do see some "foamy" substance appear and i take it these are bubbles that shouldn't appear under load but do they at idle?

waiting for friend to check with gauges to check my pressures and i realize that is a big step to check but in the meantime wondering if anyone has any other suggestions??!!

thanks again for all your help! mike
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