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jomap · Jul 21, 2013, 12:43 AM

Found the leak in my central ac system. Now, evacuating the system in preparation for charging it. Vac pump pulls a good vacuum and the system holds it. Have shut off pump and isolated system several times with a vacuum still on the system. I let the pump run for about a half hour 3 times. When I first start the pump, the oil is very agitated. But it very quickly settles down and the pump pulls a good vacuum. Even after several vacuum/sit cycles, I still see small bubbles coming up through the oil in the vac pump. Is this due to the normal operation of the pump or is it water and other noncondensables being pulled out of the system? Plan on letting it sit overnight with a vacuum on it. Hope this will pull all of the stuff out of a system which has been sitting for awhile. Also, the plate on the condenser unit says the charge is 7 lbs 15 ozs. Should I aim for that weight coming out of my refrigerant tank or are there temps and pressures to watch for along the way which would be a better determination of how the system is working?

Grady White · Jul 22, 2013, 07:11 PM

If you are not using a micron gauge to measure vacuum, you are kidding yourself.

jomap · Jul 23, 2013, 02:03 AM

Wish they had a "thumbs down" option. If you think your answer met the goal of a website entitled "ask me help desk", you are kidding yourself. I asked a couple of questions. Your answer doesn't fit either of them. Anyway, my system seems to be working. It's putting out air in the mid to upper 50's at the register nearest the evaporator. Thanks for your "help".

Grady White · Jul 23, 2013, 06:45 PM

Don't come crying to us when the compressor craps out due to moisture in the system.

ballengerb1 · Jul 23, 2013, 07:05 PM

I think what the OP is saying is he asked several questions and you have offered absolutely no help or answers. He may not have your skill or equipment but thas why he is here asking questions. Why not offer some suggestions

jomap · Jul 23, 2013, 07:25 PM

Originally Posted by Grady White

Don't come crying to us when the compressor craps out due to moisture in the system.

And just how did you read my initial post and come to the conclusion that I didn't use a micron gauge to measure vacuum? Where is there any mention of that except in the conclusion to which you jumped? Still no answer to any of the questions. Still wish they had that thumbs down option.
If you read my questions, you will see the first one is exactly about trying to rid the system of moisture/noncondensables and thereby avoiding compressor problems. After running the 3 vac and sit cycles, and letting it sit over night with an undiminished vacuum on it, I ran the vac pump again. I still observed small bubbles. Since my question remained unanswered, I had to make a call myself. I decided if all that time overnight had not flashed moisture to vapor (and thereby reduced my vacuum), then the small bubbles must be the result of normal vac pump operation.
Also, for info, the leak was a loose Schraeder valve left by one of the local "hvac professionals". If I hadn't searched for and found it myself, I wonder how much they would have charged to "find" it. Then there's still the recharge. Sometimes the pros aren't as smart as they think they are. This isn't rocket science.

Grady White · Jul 25, 2013, 06:49 PM

jomap,
Sorry if I jumped to an unjustified conclusion about your skills. I must advise you, if you are not licensed by EPA to handle refrigerants, it is unlawful for you to work on a refrigerant containing system. That being said, & to answer your question about the bubbles, there should be no bubbles seen in the oil sight glass of the vacuum pump. You could still have a leak or moisture not evidenced by the gauge on the pump or charging manifold. That's why I commented about the micron gauge.