Automotive Air Conditioning Information Forum

So I got an issue I believe its the expansion valve. I replaced a compressor. The system held pressure but the low side was all way to the max. I should of tried expansion valve before compressor. Replaced compressor trying to vacuum won't take no vacuum at all now. No problems nor leaks before new compressor now it won't allow no vacuum like there's blockage, any suggestions, using manual vacuum and gauges they all work fine. The vacuum wone even drop below -10 and soon as I close the gages goes right back to zero. Had dye in system already no signs of leakage anywhere. And also stated earlier in text held pressure fine before new compressor...

Please state the make/model/year.
It is possible that your couplers are not making proper contact with the AC ports. Lower priced couplers are known for this problem. It is also possible you have a sizeable leak.
Is your vacuum pump driven by electric motor?

It is an 08 Altima the guages were working fine before I released pressure out the system to change compressor. It will hold charge when the valves are closed and not connected. (Meaning just off of vacuum). There was no sign of leak before I changed the compressor. Now it's like it won't allow it to vacuum like there's blockage. The vacuum pump is electrical and it's vacuuming. It will stick to palm of my hand when turned on (the guage)

The connection of your hoses at the ports is still suspect.
Be sure the thumb wheels are turned all the way clockwise.
This is a common problem. Unless you get high quality connectors such as Robinair, this can be a problem. Ask me how I know.