Ok, now that we have all the history on my ac problem (yes I said problem and not issue) on another post, a fellow member suggested I start a new thread. For those of you that have not read my previous post here a link to it--àhttp://www.peachparts.com/shopforum/vintage-mercedes/321827-ac-climate-control-ii-problem-1978-300cd-diesel.html.

I can not get but 6oz if gas in my system. I have pulled the compressor again and will pull the dryer/accumulator and drain oil in both. Below is what I will do:
1. I will drain oil from compressor and I will pour 4oz Ester oil in the low side of compressor and 4oz in the dryer. Actually 1oz of the 8oz is ICE 32.
2. I blew compressed air from the compressor high side line through the condenser and out to the dryer input (but not through the dryer). Air flow was good.

• I blew compressed air from dryer output line through expansion valve. Volume of air did not flow out the compressor low side line as fast, but it is open. I assume this is because the expansion valve has a very small output so that it will not create too high pressure back to the compressor. Should the expansion valve be open or closed for this test? Ambient temp was 95degrees.
• I will install compressor and new o-rings and pull vacuum for 1 hour.

Now before I re-install the compressor, do any you have any suggestions before start this laborious task? I will wait for your reply before I go to the next step. The system was convert to R134a several years ago. This is not a "Junk" car take a look at my pics http://www.peachparts.com/shopforum/vbpicgallery.php?do=view&g=2631

Did you stick your finger over the suction port of the compressor and turn the shaft by hand to verify your compressor is functioning? If there is suction, I'd repeat on the discharge port and make sure there is pressure.

From your previous post:
6. Low side pressure 90lbs (very high) should be around 45lbs
7. High side was 98 lbs (very Low) should be around 250-300lbs

Those two are very close - almost about what the static pressure of the system would be. It makes me think your compressor isn't compressing.

Are you 100% sure the compressor clutch is engaging?

Yes the clutch is engaged. I forced the clutch to engage by connecting the two wires together at the high pressure switch on the dryer. I have the compressor on my work bench. I put the caps back on the compressor and turned the shaft a few times and when I loosen the cap I could hear it releasing pressure. Is it possible that the high and low side inside the compressor could be bleeding out from the high side to the low side? Thanks for your reply.

I guess it's possible, but a finger over the suction port and a finger over the discharge port will tell you conclusively.

Yes, you should be able to feel a pronounced difference. Like others have said, Yorks are pretty robust. The only other thing it could be is an expansion valve issue because it is responsible for maintaining the proper low and high side pressures. With a bad expansion valve, the high side pressure goes from the dryer with only slight resistance through the Evaporator and back to the compressor, meaning the A/C compressor is literally nothing more than a pump and the slight resistance of the dryer, condenser and evaporator account for your slight pressure differences. Your expansion valve is almost surely stuck open. If it closed, and your compressor were bad, you'd STILL get up to 150 PSI on the high side (unless it were locked up).

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Possibly dirty filter screen at input of expansion valve...

Thanks for giving me a way to test my compressor. I tried the thumb over the low side and did not get a definite feel for suction. I cut the fingers out of a rubber glove and put on the low side and high side. Both rubber fingers were collapsed. I turn the shaft with my all purpose tool (vice grips) about 20 times. The high side inflated enough that I could tell it was pumping. Now for the surprise the low side did not create suction, it created enough force that it blew the rubber finger off the port. Looks like it is going back to my vendor. If they don't warranty the compressor because licenses certified person did not install it, I will name the vendor. It must have been DOA. I tried to upload pics of the test, but the upload failed.

__________________
Bob Fowler

If I could make a suggestion ....

This might be a really good time to upgrade from a York compressor to a Sanden or Seltec rotary compressor. You would need a York-to-Sanden bracket ($40) and would probably need new hose ends.
I believe you said you are running R-134a so a new set of barrier hoses makes sense (R-134a leaks through the old R-12 hoses).
Also, if you are converting to R-134a, replacing the tube-and-fin compressor with the new style parallel flow condenser will improve the efficiency of the system.

I realize those suggestions add $$$ to the project but I just thought I'd give you some advice from someone who has "been there and done that".
http://www.peachparts.com/shopforum/vintage-mercedes/224997-r-134a-conversion-success.html

If i blow compressed air into the hose from the dryer through the expansion valve and evaporator, will the amount or air coming back to the compressor be reduced? If yes, does this mean the expansion valve is working OK? If the air flow should not be reduced, does this mean I may have a slight blockage in the evaparotor and or expansion valve?

__________________
Bob Fowler

I admit I find the theory of expansion valves hard to understand, but I don't think it's as simple a test as blowing air through one side. I think that pressure, suction, and temperature all come into play.
Her's some more info:
Thermostatic Expansion Valve (TXV or TEV) ? This Is How It Works

I don't know of any way to test it - It's a $30 part and I usually replace it on principle when the system is opened.

********e would not replace the compressor because a AC Certified person did not install it. I told them that the car never made out of my garage because I could only get 6oz of gas in it and the low side pressure shot up 90lbs and high side did not get over 110lbs. I also told them my bench test with the rubber glove fingers failed due to low side creating pressure instead of suction. Still did not get it replaced. I ordered a new compressor from another vendor that did not require AC certified installation. Bench test on this compressor passed the test. I will install compressor on 8/12. Will let you know the results.

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Bob Fowler

This is why you should buy parts from this forum and not a fly-by-night operation

I'd do a chargeback personally. It's not like you had it on for any period of time & it failed due to user error (no vacuum being drawn prior to fill, no new dryer, etc).

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Thanks to all. I now have cool air....I see a lot of issues posted but few resoultions. My solution was order another compressor. Yes the last one was bad and ********e would not replace. I installed and charged today....Works great. Thanks to all that helped me on this. Lot of good minds out there.

__________________
Bob Fowler