Weird R4 Compressor Behavior - PeachParts Mercedes-Benz Forum

sailor15015 · #1 10-04-2007, 10:41 PM

I have a rebuilt R4 compressor that I installed in my r12 system almost two full years ago now and it suddenly quit working this week. The odd part is, though, is the way that it quit working. The clutch and everything still engages like its supposed to but it doesn't turn the inner workings of the compressor. I hooked up my gauges and both high and low sides stay in equilibrium, showing that the insides of the compressor aren't turning. Is there maybe some nut or bolt on the face of the clutch that could have come loose? The only indication of anything out of the ordinary was that occasionally the compressor would cycle really quickly, like five times a second. It didn't make any "rock tumbler" noises or give any other indications that it was about to fail. Thanks in advance.

vstech · #2 10-04-2007, 10:45 PM

the reed valves could have failed... that would cause equilibrium without seizing.

sailor15015 · #3 10-15-2007, 12:45 PM

Well I guess my compressor is pretty much toast, which sucks because it was working so well right up until it quit. I've come across a new compressor that's lacking a clutch. Is it hard to swap a clutch on these compressors? Is it just a simple bolt or two or is it a major job requiring special tools? This compressor is cheap and I'd like to snag it if swapping the clutch is no big deal.

rrgrassi · #4 10-15-2007, 12:49 PM

The clutch is pressed on.

sailor15015 · #5 10-15-2007, 12:50 PM

Really? I thought it was bolted. Dang.

rrgrassi · #6 10-15-2007, 12:54 PM

It's usually held on with a bolt as well. Be careful though, as I have seen the clutch sell for the same price as a compressor w/a clutch. Two years is a good life for the R4.

sailor15015 · #7 10-15-2007, 01:04 PM

Thanks. Now that I think about it, I have a junked compressor that came with my wrecked car. I'll have to see how hard it is to get a clutch off. Could I expect a new compressor to last longer than two years? This one was a rebuilt. I'd hope to get longer out of a new one but if not then I'll just go with a rebuilt again.

didget69 · #8 10-15-2007, 01:54 PM

"Rebuilt" is a generic term, often over-used... Is a replaced set of seals considered 'rebuilt', or is the addition of seals & new bearings considered 'rebuilt' or is every wearable item dimensionally checked or qualified
for reuse in the rebuild, or ???

This is why I'd recommend ONLY new R4 compressors... might cost you a bit more on the frontend, but compare it to the cost of replacing "rebuilt" units every few years. My original R4 compressor in my '84 123 car lasted 21 years on it's original R12 charge -

bnc

tangofox007 · #9 10-15-2007, 05:44 PM

Quote:

Originally Posted by sailor15015

Could I expect a new compressor to last longer than two years?

My original R-4 lasted 24 years, six of those years pumping R-134a. And it was still working when I replaced it with a new one last year concurrent with a "conversion" back to R-12.

FRANKNBENZ · #10 10-15-2007, 05:49 PM

didget69, (or other forum folks)

I'm planning on two R-4 R&Rs for the 85's. Any tips on good sources for new? Noted in some web searches this is a Frigidaire unit and comes two ways, one with "stepped" ports. Which is the best fit for the 85 300D?

Thanks.

tangofox007 · #11 10-15-2007, 07:53 PM

The stepped ports are best avoided, if possible. I was unable to find a new R-4 that used the old seals, however.