Recently had compressor lock up. Can't complain since it lasted 15 years without any trouble.
To complete the replacement I have replaced compressor, condenser, accumulator and pressure switch mounted on compressor. But first I flushed all garbage out of system twice.
I am having trouble getting it to hold vacuum so I can get a dry refill.
I am able to get enough Freon into system to obtain about 39 degrees at the center vent. Put dye in the system but found only one leak at inlet of accumulator. Fixed that problem but still having issue.
Replaced all the O-Rings and seals again and even tried a 2nd new accumulator. No signs of dye "seepage" on any of the O Rings I replaced on second try except the accumulator inlet that I knew about.
Here is what I have found after much trial and error with vacuum pump and gauges.
I can only get about 24 vacuum then it drops to 22 then 24 then 22. Like something is opening up between 22-24. If I close high side gauge will jump about 2 higher but still do same thing but slower.
If I close off gauge the vacuum on system drops quickly. Hits zero in only a few minutes.
Verified vacuum can pull 30. Check gauge fittings etc.

Vehicle is 2000 Blazer ZR2 4WD with 4.3.
Thanks in advance for your help.
Mark

 

When evacuating, it needs to be done through the low side only, the high side valve on the manifold set must be closed. Should pull two atmospheres, (29.4"hg) within a couple of minutes. If not, add UV dye and 1# of R134a refrigerant. Using a black light, locate and repair the leaks. When the leaks are repaired, evacuate for a minimum of one hour, and charge with 1# 12 ounces of R134a refrigerant.

 

Either way it wont get lower than 24 then leaks down after valves are shut on gauges. I have redone all the connections. Where could the leak be?
BTW: All parts are brand new AC Delco and Delphi. Nothing rebuilt.
Could the leak be somewhere in the brand new Delphi compressor?

 

If the evacuator is capable of pulling 2 atmospheres, and you can only get 24", the leak could be anywhere. Using the dye and a black light will locate it.

 

Compressors are tested before they leave the factory. You said you flushed the system twice. The thinnest metal/weakest link is in the evaporator. An evaporator leak is hard to find unless you shine the black light on the puddle under the truck from your condensate drain.

 

Ice cold on the way to work today. When I started truck to head home the engine stalled as soon as compressor tried to engage. Turned off A/C then engine ran fine.
Drove home without A/C. Looked at it when I got home and sure enough, it was completely locked up. Could this be related to the inability to hold vacuum to charge?

 

I checked the puddle for any glowing. Didn't see anything but I'm sure it would take a month of leaking before enough leaked to show.
Not ready to pull dash until all other possibilities are exhausted.

 

The dye has shown no visible leaks except the one on the accumulator inlet that I corrected. The only places I can't see is evaporator and around shaft of compressor. Not ready to pull dash yet!
Compressor locked up today (Brand new Delphi) so that will have to get replaced. Hopefully it was the problem all along.

 

System oil capacity is 8 ounces of PAG150. Too much or too little oil will cause poor performance/cooling, and can cause the compressor to fail prematurely. The compressor does not have a "crankcase". The oil is in suspension with the refrigerant. Some compressors, not all, come with oil in them, usually 1.5 ounces. The remaining 6.5 ounces of oil is distributed between the evaporator, condenser, accumulator, and lines. There are some Youtube videos that show how to flush the oil out of each component. Then you can measure and install the correct amount.


AC stalling the engine is a good indication of too much oil in the system.


EDIT: Oil can be pressurized, but not compressed. As a result, it will "slug" the compressor, and usually destroy it.

 

I have a Helm factory service manual and followed the capacity figures precisely. I even drove to five different stores to find a measuring cup with milliliter's and an overall size that would allow me to be more precise with the measurement. The whole system was cleaned out so getting that correct was one of the easier things to accomplish.
As part of the repair I drained the oil out of the compressor and replaced it with new measured amount.
When I re-replaced all the oil rings I noticed good distribution of the oil through out the system.
This is what is so frustrating. I took extreme care. If I had rushed head on into the repair, I probably would have had no problems!