Compressor failed spectacularly - PeachParts Mercedes-Benz Forum

Demothen · #1 07-24-2016, 08:26 PM

Had the compressor filled at or slightly below operating pressure, about 85 degree ambient. Was looking for leaks in the cabin with the engine idling and the AC on, had only ran for a couple of minutes. Without warning the system discharged rapidly. I shut the car off and ran while it cleared out. The r4 compressor split open where the rear piece met the body. It actually forced the main O ring out between the case seam. I am going to have to replace my parallel flow condenser that has about 1 hr of operating time on it probably, will be returning the compressor, and upgrading to a sanden kit with 100% new lines for the entire system, and replacing the (possibly leaking, not sure) evaporator.

At a cost of around $2k when all is said and done...

Will post pictures of the failed compressor when I pull it out.

BillGrissom · #2 07-24-2016, 09:45 PM

It the shaft still turns and no rattling sounds, the compressor hardware is probably fine. If true, I doubt it sent anything into your condenser. Sounds like one of the circumferential O-rings just extruded. Big suspicion is that the rebuilder's used the wrong size. As I recall, the R4's outer steel shell just slides over the aluminum guts, and the only thing securing it is some bent tabs. If it slides too far either way, an O-ring can blow out.

For $2K, you must have had shops involved. I put a Sanden on my 1985, w/ new hoses, and probably spent $300 total ($200 Rollguy's bracket, $50 new compressor, barrier hose from ebay). I kept the R4 on my 1984 and probably spent $50 on new hose, oil, and refrigerant.

Demothen · #3 07-24-2016, 10:01 PM

I guess I could save a ton on hoses by making them myself and buying/reselling a crimper. Or I may send all of mine out to be rebuilt (30-50$ each roughly to be rebuilt)
New condenser kit was on the pricey side at ~300 including brackets and hoses for it.
Compressor with brackets and new high side hoses I was considering is 600$. How did you get a sanden for 50$?
New evaporator is about 250
Considering an oversized aux fan for 150$. Or i can invest time in sourcing and rebuilding a w126 fan and making it work.
Might need another condenser. Will depend what the failure mode was on the compressor.
Hoping to return the failed r4 and get my money back, depends on if i can find the receipt and/or if the parts place will help me out. I am a regular there so pretty hopeful they will help.
Ugh. 4 or 5 driers now, one was ruined trying to remove a sensor plug that was painted in. One replaced with the drier last year, one after rebuilding the system and finding it was clogged, one more when I upgraded the condenser, and now one more thanks to having to reopen the system now that my compressor com-ploded.
And some oul, r134a, and having the system evacuated.

If I EVER touch ac again after this, I will be replacing everything upfront that MIGHT be bad.

compu_85 · #4 07-25-2016, 12:02 AM

Yes, the R4's case just slips over the body. If there's no metal filings in the system your condenser is fine.

-J

funola · #5 07-25-2016, 08:42 AM

What kind of compressor was it, new or rebuilt? Where did you find an evaporator for $200? They are nla from MB. Here's a NOS genuine unit starting bid $750

Mercedes A C Evaporator W123 OEM NIB 000 830 46 58 | eBay

Demothen · #6 07-25-2016, 08:44 AM

Brand new compressor.
Klima Design Works | W123 Evaporator

DeliveryValve · #7 07-25-2016, 08:56 AM

Sorry for your troubles... Question, did you install this bolt supporting the high pressure line?

.

Demothen · #8 07-25-2016, 09:33 AM

Yep, I installed that bolt.

funola · #9 07-25-2016, 09:48 AM

What were the hi/ low pressures on the manifold gauges when it blew? I recall you said the last can of R134 was leaking. Was it possible air got in due to the leak? Did you purge the yellow hose between cans?

Do you have the HF manifold gauge set? I have found that you need to use pliers to snug the fittings a bit more than just finger tight otherwise they could loosen up on you if you move the gauge set around. Did you pressure test the gauge set (easy to do with a tub of water) before use to insure it does not leak?

The quick couplers have o-rings in them. They must be well seated and not chewed up.

DeliveryValve · #10 07-25-2016, 09:50 AM

Does it look like this?

ROLLGUY's thread of his start to explore the use of a Sanden compressor.
I should have known better than to try to bring the GM R4 compressor back to life

.

funola · #11 07-25-2016, 10:00 AM

Quote:

Originally Posted by DeliveryValve

Does it look like this?

ROLLGUY's thread of his start to explore the use of a Sanden compressor.
I should have known better than to try to bring the GM R4 compressor back to life

.

Just read the linked thread's first post. He said: "with the exception of a bad Klima relay, so the compressor was hot-wired". Don't know how the compressor was hot wired, but if it was hotwired to be always on, that may have been cause of the compressor blowing up.

Demothen · #12 07-25-2016, 10:00 AM

Did purge the yellow line. Possibly it leaked, but I cant imagine much if any air got in while it was pressurized. Really dont know the manifold readings on the day it failed. The previous day it was charged to correct pressure for thr ambient, but on the day it failed I had just started the car about a minutr earlier and was still in thr cabin. I had run it about an hour the day before but was not getting very cold air (55 to 60 or so). I did wrench tighten the manifold set, and ran the sniffer around it, but I didnt think to run it under water. We never actually got the full 80% capacity recommended for 134a into it.

It looks exactly like that DelveryValve. Except I had recently flushed the system and added the proper amount of oil per the FSM. Also mine had oil that blew out with it.

I may take it to an indy to fill this time, so they can go by weight off of a large bottle not a can.

Demothen · #13 07-25-2016, 10:03 AM

My Klima relay is unmodified. The compressor does cycle properly. It also had a new pressure switch. I did jump the aux fan temp switch to make it run always on while I was testing, and I had a ~18" industrial type fan blowing at the condenser.

Demothen · #14 07-25-2016, 02:51 PM

New evaporator may be out of stock. I just ordered the compressor kit, an upgraded fan, and a set of crimpers for full size hoses. The person who was advising me said that the liquid line to the TXV needs to be reduced hose, and since that die costs about as much as it would to have the hose rebuilt, I'm just going to ship them the hose to rebuild for me - but I'll be replacing all of the suction side hoses, and between my PF condenser kit and the Sanden kit all of the high side hoses will be new. Also have all the ferrules and new ends for the hoses, except the custom bits for the suction lines that I'll have to re-use as they are not available. Will be getting some full sized #12 hose shortly as well.
The guy I was talking to advised me to take the evaporator in to a radiator shop to leak test, in case they are not able to source me a new one. If it is leaking, they said a shop might be able to repair it for me. I know it's a ton of work to pull it, but I was also pretty underwhelmed by the air speeds I was getting out of the vents, so even though I cleaned the coil with foaming cleaner, I might as well pull it to clean at the very least.

97 SL320 · #15 07-25-2016, 04:47 PM

Quote:

Originally Posted by Demothen

Yep, I installed that bolt.

More importantly, did you install a hose that uses that bracket? This bracket keeps the compressor can from sliding off. If the can did slide off, I would not call that a compressor failure, more of an install issue.

If the body o ring was too small, it would have leaked from the start, if too large the can would not slide on or o ring get cut during install at the factory and leaked from the start.

What were your low and high side pressures?