I had a lot of fun last week working on the El Camino. I noticed the AC was not working at all, and started investigating. No compressor compressing anything so no cold air. Rats.
I was hoping for a simple solution, but no luck. The refrigerant had all leaked out, that is the first time in 31 years and 378,000 miles it all just leaked out. So I pulled the orifice tube, and it was pretty bad and had metal pieces on it. Crap.
I put in a clean orifice tube (they are about 4 bucks) and sealed it up, and pressurized with nitrogen to 120 PSI and looked for leaks.
This is a single frame from a video I shot of the back of the compressor and this is a port that is only used in the rebuild of the compressor, and it was leaking. Not a good sign. Dead compressor. It was 11 years old and noisy as heck, so not a major surprise, but it failed totally.
OK, now I "get" to just go ahead and have two new hoses made as they were kinda old and tired. Get a new R4 compressor, flush the heck out of the condenser, replace the accumulator, new o-rings, and pull a vacuum. I can get down to 200 microns, but if I turn off the vacuum pump it starts to rapidly climb. Hmmm. Another slow leak hiding from me.
I spend a day squirting the lines and parts of the system with soapy water with the system pressurized with 120 PSI of nitrogen. I even had to go swap my nitrogen bottle with a full one as I used up my nitrogen supply.
Finally I removed the connection to the high side to eliminate that as a source and it held pressure and a vacuum. So it came down to this little adapter. All I can figure is the designers of the AC system made the high side fitting something that was not a standard AC hose fitting to prevent stupid people from trying to add refrigerant to the high side. To hook up the hose, I have to use the adapter. This one has a swivel, and when I looked real close, soapy water bubbled out at 120 PSI. Ah ha, the leak was found! I will try to find one that does not leak.
So I pulled a vacuum, purged one more time with nitrogen, pulled a vacuum until I was down to 190 microns, and let it sit overnight. In the morning it was at 208 microns. I hooked back up the adapter and pulled a vacuum to 200 microns again, and charged it up. I figure I lost a tiny amount of charge from that adapter, but it was a very small amount.
The new compressor is a ton quieter. I will have to wait until a HOT day to do a final charge, but the AC blows cold again. Not hard to do when it is just 70 degrees.
With a new accumulator, new orifice tube, three purges with nitrogen, and a 200 micron vacuum, I have the moisture out, and all should be good.