Did I get a bad CompressorWorks compressor?
 

I posted back in April asking for opinions on restoring the A/C on my barnfind 82 300D. I went with the general concensus which was "replace almost everything".

What I Did:
New CompressorWorks R-4 from Autozone (added 1oz mineral oil and rotated about 30 times)
New OEM expansion valve
New Behr receiver/dryer
Flushed all lines with 3 cans of flushing solution (no traces of metal came out)
3 oz of 525w mineral oil in suction line
2 oz of mineral oil and 2 oz of FrigiQuiet in RD
New O-rings w/ Nylog

Pressure tested system with 80psi dry air (held for 2 hours with no needle movement)
Ran vacuum pump for 12 hours (down to 275 microns on Robinair thermistor gauge)

Filled system with 3.5 cans of R-12 (underhood sticker called for 2.6 lbs)
Nice cold air at the vents and a quiet compressor

What Happened Next:
Drove about 10 miles at 9:00AM right after filling the system.
No problems noticed .......Job done, right?
Wrong.

Drove about 10 miles in 95 degree heat that afternoon and got stuck in traffic..... A/C not able to keep up with the blazing sun and ambient temps.
The compressor seemed to be putting a heavy load on the engine.
At the next traffic light, the engine stalled. I turned the A/C off and restarted.
Didn't turn the A/C on until underway... still not cooling so well.
When I slowed to turn into the driveway, I heard a creaking/scraping sound ....it was coming from the compressor.
After a 6 hour cool-down, I checked pressures:
90 psig static pressure
35-40 psig suction and 200 psig discharge while running (I only ran it for about a minute because the compressor was still making noise).

So what did I do wrong?
Too much oil (8 oz total)?
Too much refrigerant?
.....or was the shiny new compressor a dud?
I'm completely bummed-out ..... I've spent weeks assembling all the parts and tried to do everything just right, not to mention all of the money and sweat expended on this job.

The can was probably 12oz. My math may be fuzzy though

1oz of in the compressor was prolly not a great idea. I would have put about 4 oz of oil the compressor.

I think he meant 3.5 cans of R12

Yes ..... 3.5 12 oz cans.....about 42 oz as best I could tell.
I actually added 1.5 oz of oil to the compressor, but about 1/2 oz ran out while trying to connect the hose fitting.
Another 3 oz added to the suction line.

I went through the same thing last year with my 300e. Turned out the gap on the clutch plate was not correct, and got stuck in the engaged position until in went kaput. Had to start all over again.

Maybe check the gap, it could be too far out, causing it to slip?

What is/was ambient temp? Seems like the high side is a bit low.

... define dry air...

if you indeed got 275 microns on a mobile refrigeration system, your schrader valve is not opening enough. rubber and designed leaks will not allow that deep a vacuum...

likely you sucked and sucked, and the schrader closed up partially, and you were reading the micron of the manifold only.

12 hours of vacuum is a very bad idea in a mobil non hermetic system. I'd limit to 1.5 hours max.
usually 30 minutes is sufficient. additional time just draws moisture into the system. likely your dryer is wet, and acid buildup is not far off...

Did you drain the initial oil charge out of the CompressorWorks prior to filling with mineral oil? IIRC, the CW unit says "for 134 only" and may have had a small PAG charge.

Did you condition the new clutch as recommended with repeated on/off cycles?

Does the grinding sound internal or from the clutch?

Since you include stalling, I'd speculate that something is causing the compressor to seize or overpressurize. Did you re-use the pressure cutout switch on the R/D? How is your Aux fan? What was your coolant temp showing?

... define dry air...
Compressed air through a dessicant cartridge(normally used for a paint gun).
I should have added that I did the pressure test using the OLD dryer. I was mainly worried about leaks at the compressor seals.
I installed the new dryer before vacuuming the system.

if you indeed got 275 microns on a mobile refrigeration system, your schrader valve is not opening enough. rubber and designed leaks will not allow that deep a vacuum...
I was skeptical about the 275 number myself. This was using the older Robinair thermistor gauge with the row of LEDs.

likely you sucked and sucked, and the schrader closed up partially, and you were reading the micron of the manifold only.
I suck at A/C work, that's for sure.

12 hours of vacuum is a very bad idea in a mobil non hermetic system. I'd limit to 1.5 hours max.
usually 30 minutes is sufficient. additional time just draws moisture into the system. likely your dryer is wet, and acid buildup is not far off...
Would this account for the compressor noise?

Man, whatever happened, that sucks :(

I've heard that Compressorworks R4's are good, I've heard they're bad... :confused:

Whatever happened I hope they'll honor their warranty, but there's still all that work...

That noise you hear is the compressor clutch slipping because of the compressor "loading" up or it is not holding in when it gets hot. Was the condenser fan operating at the time? Put the gauge set back on it and let us know what you got.

"Burnish" was the word I was looking for. From my install thread:

This is what Ryder says about burnishing: “Burnishing is the cycling of the clutch to allow a wearing in of the engagement surface area. The reason for burnishing a clutch is to increase the initial starting torque. Most technicians fail to follow this important procedure when replacing a compressor or clutch. An unburnished clutch can produce a low torque condition, causing the clutch to slip and thereby fail. When replacing a clutch or compressor & clutch assembly, follow this important burnishing procedure. Run the engine at 1,500 to 2,500 RPM. Using the controls on the dash, cycle the clutch ON and OFF at a rate of 10 to 15 times per minute for a total of 50 cycles minimum. This should bring the clutch up to operating torque capacity.”

:confused:

:confused:

Did you ever find the problem? I just installed a Compressorworks R4 and immediately had a clanking sound from it when it's engaged. occasionally it will slip the belt for a second. I'm thinking there's not enough oil in the system, since a good bit came out while installing the manifold lines. I also stuck with R12.

Willson
85 300CD

is it the right kind of R-4 compressor for Mercedes? the regular R-4's (for GM, etc) are mounted differently (upside down/ rightside up, whatever you wanna call it). so if someone installs a regular R4 compressor in a Merc it will lock up in short order since the sump is in the wrong place. i've seen several places that sell R4's saying its for a Merc when its actually not