evaluating an AC compressor when system is currently discharged - Page 9 - PeachParts Mercedes-Benz Forum

97 SL320 · #1 05-31-2018, 04:36 PM

A slower AC compressor could lead to reduced cooling at idle. Other than that, no big deal if the pulley does not rub anything.

kuene · #2 06-02-2018, 11:28 AM

COOL.

Also my car is cool! Now I need to attend to this loud aux fan before it craps out. I think a cleaning/lube/greasing of bearing/motor is in order.

Diseasel300 · #3 06-02-2018, 12:05 PM

If the W123 fan has anything in common with the W126 fan, you have a ball bearing and a bronze sleeve bearing. Don't grease the bronze bearing, you'll ruin it. Oil for electric motors ONLY (such as Zoom Spout oil or 3-in-1 in the blue bottle). The ball bearing is typically not a sealed bearing and is better to be replaced than lubricated.

kuene · #4 06-02-2018, 02:00 PM

I found a fairly straightforward clean/lub pic walkthrough in on here that seemed to be well received.

kuene · #5 07-06-2018, 04:57 PM

just giving an update - my refurbished AC system with the slightly incorrect r4 compressor (pully is half inch too big) is still running nice and keeping me cool. And I haven't even swapped out the r134 for my r12 yet. Cooling is great!

Maxbumpo · #6 07-09-2018, 06:15 PM

bottom line up front: your compressor may be upside-down, and will have a shortened life due to improper oil flow inside the compressor.

Please read my post in this thread, it is #6:

A/C - HELP! - 1985 Mercedes (W123) A/C Washer Sealing

Further, my understanding about the manifold seals is that MB specified the metal seals because the increase vibration of the diesel engine caused the plain old rubber seals to fail prematurely. I am not sure what type of seals your compressor has, but some of the commenters in this thread recommended the rubber seals, and I think that is incorrect.

vwnate1 · #7 07-09-2018, 09:05 PM

? I thought the whole point of the R4 compressor was there's no oil resivoir, the oil travels with the Freon making how you install it irrelevant ? .

ROLLGUY · #8 07-09-2018, 09:42 PM

Quote:

Originally Posted by vwnate1

? I thought the whole point of the R4 compressor was there's no oil resivoir, the oil travels with the Freon making how you install it irrelevant ? .

It makes sense to me that the oil inside the compressor will want to flow downward because of gravity. If there are in fact oil channels that don't get oil because they are upside-down, then that would explain the short life span of "new" compressors. They may be clocked for the majority of applications (GM), so the MB application would necessitate re-clocking before installation. I assume they were clocked from the factory for MB originally.

97 SL320 · #9 07-09-2018, 11:13 PM

Quote:

Originally Posted by ROLLGUY

It makes sense to me that the oil inside the compressor will want to flow downward because of gravity. If there are in fact oil channels that don't get oil because they are upside-down, then that would explain the short life span of "new" compressors. They may be clocked for the majority of applications (GM), so the MB application would necessitate re-clocking before installation. I assume they were clocked from the factory for MB originally.

The R4 is like a 2 stroke engine where oil is carried along with the freon. With R12 mineral oil would mix with the freon allowing it to circulate through the system.

Mineral oil won't dissolve into R134 and that is why other oils are needed.

It's been a while since I've had a R4 apart but I don't recall any internal sump. The only thing to " clock " would be the clutch coil plug and maybe the shaft seal housing as the outer case is entirely round and hose connections part of the main housing.

ROLLGUY · #10 07-10-2018, 12:20 AM

Quote:

Originally Posted by 97 SL320

The R4 is like a 2 stroke engine where oil is carried along with the freon. With R12 mineral oil would mix with the freon allowing it to circulate through the system.

Mineral oil won't dissolve into R134 and that is why other oils are needed.

It's been a while since I've had a R4 apart but I don't recall any internal sump. The only thing to " clock " would be the clutch coil plug and maybe the shaft seal housing as the outer case is entirely round and hose connections part of the main housing.

True there is no sump, and yes the coil connection needs to be clocked for each particular application. I have not looked inside an R4 for a while either, but as you say, the shaft seal housing may need to be clocked as well. It may very well have the oil hole in it that needs to be in a certain orientation. I have several R4 cores, I should take one apart and have a look for myself.....Rich

vwnate1 · #11 07-09-2018, 09:48 PM

Thanx Rich ! .

AC, like carburettors, really should be done by someone who's doing it on a regular basis .

I stopped doing big American 4BBL carbys in the 1980's and don't miss it much .

I still fiddle with 1BBL Webers and Solex's, Rochester B and MV series carbys on the older stuff I have but if you're not doing it frequently the details sorta slip away .

kuene · #12 07-10-2018, 11:03 AM

Yeah I give up. Shouldn’t have wasted my time. It was great having ac for a couple months though but I see that my system is likely doomed.

Maxbumpo · #13 07-10-2018, 02:16 PM

Quote:

Originally Posted by kuene

Yeah I give up. Shouldn’t have wasted my time. It was great having ac for a couple months though but I see that my system is likely doomed.

Not so fast, you've just learned more and now have some more work to do. If you address the possible issue now by pulling the compressor and checking to make sure the oil bore clocking is correct, you can probably get years and years of service from it.