Technical AC system won't hold vaccuum, but holds pressure?

VA instructions say their compressors are shipped with correct oil. Some say the rotate the compressors by hand before charging

 

Most likely. Check the instructions on the vacuum pump. I know I had to fill my oil sump up because it had gotten low. It is important to have the correct oil level in the vacuum pump, too much is not good, and there is likely a change interval due to moisture contamination over time IIRC.

 

The system should seal with pressure and u deer vacuum, but success income doesn’t ensure success in the other. I saw some
good suggestions as to helping with the vacuum issue.

As @gimpyshotrods replied to a similar question, there are two bad things moisture in the system can do: 1) render your receiver/drier ineffective, and 2) mix with the refrigerant (or maybe it’s the oil) and cause acidity that will harm the compressor.

You might swap out for a new receiver/drier before you charge the system, since they’re not very expensive.

Then purge with nitrogen (typically) followed by drawing a vacuum before charging with refrigerant.

Then enjoy your AC!

John

 

From a practical standpoint it's never a good idea to use any kind of introduction of air into an AC system. To purge the system you should use refrigerant introduced on the high pressure side because the compressor flapper valves will not allow flow in the opposite direction so when you introduce refrigerant on the discharge side it will flow all the way through including the dryer to flush out air molecules and hopefully some moisture molecules. Then you evacuate again before charging.

 

Being a low budget, shade tree, do it myselfer.. I don’t own a nitrogen tank or Freon beyond a 12oz can. I’ll replace the dryer just as soon as Amazon delivers it and then charge it up. Do you think running a 12 oz can through the system would be a smart move prior to evac? Bear in mind, I have no recovery system either.

 

It could not hurt anything.

 

I assure you, you won't be contributing to global warming...OOOOPS, I mean "climate change", if you blow a can of R134A.. just don't turn the can upside down, don't ever feed liquid to a system, EVER. And watch some YouTube videos on how to charge the system. Hopefully, you bought a filter/drier with a sight glass so you can assure yourself that you are getting a good clear column of liquid feeding your expansion device.

 

Yep…got a sight glass and been buffing up on my YouTube videos. Gotta be careful with that global warming ya know…Even my new AC can’t chill all the hot air coming out of DC.

 

Back in the day, while installing some of our pre-production rotary vane AC compressors on NYC subway cars, I watched workers walking around with 30 lb containers of R-22. I asked what was going on, and the supervisor told me they were being used to “top up” systems that were leaking. I said aren’t you supposed to fix the leaks to prevent refrigerant discharge and he laughed and said they had an exemption. Lol! Back then it was the “hole” in the ozone layer that was being destroyed by certain refrigerants. They (oil companies) were also using refrigerant to clean out the massive oil storage tanks. I’m sure they had an “exemption” as well. So don’t worry about a few ounces going into the atmosphere. Lol!

 

Lol.. as I was picking up my R134a from Autozone there was a guy “ topping off” his AC in the parking lot. I was thinking, how may millions of leaky cars get topped of every summer. Not to mention every front end bumper thumper that punctures the condenser. I’ll just get me an exemption from Autozone….lol.