Re: How to Properly Add AC Compressor Oil
The valve I was referring to was the schrader valve, it is the little pin in side the service ports. The tool to remove it is really cheap you can pick it up at any auto parts store. and it would be a good place to start to just add the recommended amount for a compressor change.
When they removed the plug from the compressor was the system full. If so them the gas was released it pulled some oil from the rest of the system. so if this is your case add about 1/2 oz per lb of refrigerant on top of what is needed for the compressor.
And when pulling a vacuum on the system, let the vacuum pump run for at lease 30 mins, even thou it will go down to 29.92" Hg of vacuum in like 1 min. and mark the gauge and let the system sit for like 30 mins untouched to see if the gauge moves at all. If it don't move you are good no leaks and its ok to refill the system. And when you add refrigerant make sure you add it by weight not pressure.
I would not worry to much about the dryer just make sure you get a really good vacuum on the system to make sure you get as must air out of the system as you can and remember you can't run the vacuum pump to long. On some jobs I had to use two pumps and let them run all night long to get the system down to 300 microns.
Also, it maybe a good time to think about changing the orifice tube filter and the compressor filter as well because they are so cheap and the system it open. Its just good insurance.
If you have an other questions I will try to help, but I really don't do automotive A/C work. I have done it on my own cars but other then that I have not done any, but I do, do industrial and commercial work for a living, so for the most part they work the same just different gases and systems.