A/C compressor woes

[Edahall]

From what I understand, there has to be enough charge for oil to circulate through the system. If that is true, what keeps a pump lubricated when the system is being re-charged?

When I was re-charging the system after replacing the condenser, the compressor was sucking in the freon slower than molasses. I was about 45 minutes into it when the pump locked up. When I removed the pump, it was bone dry! Since then, I have installed a new pump and cooling performance is much improved.