R4 compressor died... - PeachParts Mercedes-Benz Forum

1980sd · #1 06-11-2011, 02:49 AM

My AC worked great for about 200 miles. No problems, no complaints. I did get low on fuel and turned it off for a few miles but it started back OK.

On the way home I noticed it wasn't cooling. Checked and the clutch was slipping. It seemed to slip-grab-slip-grab. I shut it off when I saw what was happening.

I got home in the light and figured I'd give it one more shot and it made an awful noise so I shut it off. The belt didn't squeal nor did the engine bog down.

The center part of the clutch spins free, seems too free to be a compressor

I engaged the clutch and it seemed to lock pretty well. I couldn't turn it by hand because it was engaged with the belt.

I did find what looked like the wiry edge of some kind of seal sticking out of the clutch.

Soooo

Did my compressor failure flood my system with crap that I'll never get out? stuff that can gum up the expansion valve? Is this a DISASTER?

I guess I won't really know until I open it up... Would the system bleed down if a shaft seal or something went out?

Just wanted to add that I had my fresh-air element hooked up backwards so it the evaporator was seeing "fresh air" instead of recirculated air for the trip. Don't know if it could have a bearing on "head pressure" or something...

I just put my cheap-O charging gauge on it and it's about 100 psi on the low side. I guess whatever happened didn't discharge the system.

Is it time to just start taking stuff apart? Can these compressors fail without gumming everything up?

leathermang · #2 06-11-2011, 10:15 AM

Is there another thread detailing what you did 200 miles ago ?

Yak · #3 06-11-2011, 11:11 AM

Pics would help add to the description of "wiry edge of some kind of seal sticking out of the clutch."

There's an online pfd linked from this thread that illustrates some clutch parts. Don't get confused/distracted by the different shape pulley. http://www.peachparts.com/shopforum/showthread.php?t=299985&page=2

There's also an extensive "rebuilding an R-4 compressor" thread I think by funola from last year that has lots of pics of the clutch, etc. Referring there may help ID what you mean.

1980sd · #4 06-11-2011, 11:48 AM

You referring to my "blowout" mang? Than was about 600 miles ago and it has worked fine since that episode although I've considered it suspect. The "seal" part that I found looks like it came from the coil area and I didn't see anything on those illustrations that looked similar.

I guess I'll pull the belt so I can tell more about what's going on...

Really sad because it was working LIKE A BOSS yesterday in the Ga. heat... The compressor was a little noisy (Kind of a rattling sound if you listened closely) but I had read that it's a noisy design...

I just went out and noticed that the clutch air gap appears too small even with the compressor disengaged. It's actually dragging and making noise with the switch off...

leathermang · #5 06-11-2011, 12:39 PM

"You referring to my "blowout" mang? "

You really think I am capable of mentally keeping the AC history of all the cars we talk about here on the forum ...? I can't remember day before yesterday's activities if someone starts a new thread....Every time I wake up it is a whole new world.... LOL... and I take a nap in the afternoon too....

1980sd · #6 06-11-2011, 12:45 PM

Well, My lo pressure switch was cutting in/out and I was adding some 134 via one of those cheap parts store deals. Anyway, while pulling the trigger on the charge deal something like a fire extinguisher went off under the car. (I couldn't pinpoint where it was coming from) I stopped and didn't fool with it any more but it seemed to work OK.

Then this...

I am now going to the garage to get greasy... Very greasy...

Blowout thread:

http://www.peachparts.com/shopforum/showthread.php?t=299073&highlight=blowout

Tis a sad day...

leathermang · #7 06-11-2011, 12:53 PM

So at that time didn't we assume your car had a high pressure blow off valve ?
My Lincoln has that... but can't be bought...so we had to get one from salvage yard a few months ago..
Were you reading the pressures as you filled it ?
Was the car at high idle , windows down, AC on full blast ?

One potential here from these scant facts and assumptions..
is that you overfilled it...
and while it was able to keep you cold...
it just worked the system to death...
having too much refrigerant is really a bad deal... same with oil...

engatwork · #8 06-11-2011, 01:48 PM

Quote:

134

That's all you needed to say. These cars struggle with the original (dirty evap/condenser) on 134 in the Ga heat.

Quote:

You really think I am capable of mentally keeping the AC history of all the cars we talk about here on the forum ...? I can't remember day before yesterday's activities if someone starts a new thread....Every time I wake up it is a whole new world.... LOL... and I take a nap in the afternoon too....

Sounds like me.

leathermang · #9 06-11-2011, 02:06 PM

134,,,,That sure could be it...
and wasn't there something about the procedure you followed NOT addressing the amount of oil in the system ? ie, total flush and measure oil back into the system...
That combo sure could have been deadly....

1980sd · #10 06-11-2011, 02:18 PM

There she is:

Not too bad drilling down to it.

I really appreciate the help guys! Mostly speculation at this point.

Things I've learned:

Don't just go shooting "freon" in your poorly functioning AC system using a parts house gauge with a polar bear on it as a reference.

AC systems use physics which is complicated...

From looking at the PDF from the link you provided I think there may be a blow-off valve. It may be under the clutch. But I'll see if I can check it out when I remove mine.

I have some argon for my welder so should I shoot some through the system and cap it? How long can it safely be open to air with,say, duct tape over the ends. Not sure if it'll do any good but maybe... Physics again...

I also put a can of oil in it as well as enough refridgerant to make the lo pressure switch stop kicking in. Maybe I should have stopped there...

leathermang · #11 06-11-2011, 03:17 PM

You have learned a LOT Grasshopper.....
Too bad your AC was the guinea pig...
but it can be fixed....
Argon or any dry gas to keep it sorta sealed up till you can address it is good... but duct tape...no... find an AC specialty shop and see if they have a plug which is held on by a hose clamp with a long reach tong on it.. or something like that with a threaded hole were you can put a plug into it...
If all else fails then put a fine threaded bolt a couple of inches in by screwing it in.... as big as will fit the ID of the hose...put refrig oil or nylog on the threads first..

1980sd · #12 06-11-2011, 03:37 PM

Here's the hose connection after evacuating the system and opening:

I'm not sure but it sure doesn't look like any debris from the compressor is in these lines. Would it be obvious if there was crap in the lines?

Here's the oil/dye that drained out:

That black debris is from under the car. Everything that ran out just looked a lot like antifreeze.

Does this tell us anything? Gotta plug those hoses now...

leathermang · #13 06-11-2011, 03:44 PM

Well, clearly ( or mostly green slim color ) we do not suggest DYE for your system... maybe it was already in there... but it is unnecessary in the first place....and not the best way to find a leak in the second case...
When you do flush your system... you need to use filters going into the jar the flush is going into... to catch any things like shown that might be in the lines ...just so you can examine them...
That is WAY TOO SMALL of a test to be determining anything...
Don't jump ahead either direction this time ...
PHYSICS !!!!
Conservative procedures, cleanliness.....

1980sd · #14 06-11-2011, 04:00 PM

Do I need to get to the expansion valve and fool with it or can I just flush it from where I am?

I did find a problem with the compressor which I'll show in a vid. that I'm uploading. It'll show it better than I can describe.