About a week ago, the evaporator coil started freezing up, restricting the air flow. I cleaned filters, coil, etc. No change. Decided that some of the freon charge had been lost. Found oily residue around a connection, cleaned and tightened. Evacuated and pulled a vacuum on the system for an hour and a half or so. After adding about half of the R-22 that the system requires, I switched every thing on. Pressures seemed to be OK, albeit somewhat low as would be expected. Slowly started adding more gaseous freon to the low side. Suddenly low pressure shot up to equal that of the high side, around 120-130 psi, where it stayed whether the compressor was on or off. After setting overnight, in the cool of the morning, both sides were at 70-80 psi. Turned on unit on, neither pressure changed. Compressor sounds the same as ever. Do I have a bad compressor, blockage or?

If it's a system with an expansion valve... it could be stuck open. Or it could be a compressor failure. Particularly if it's a system with an orifice.

The system has capillary tubes.
I believe that I may have found the problem though. The freon charge was obviously low from the problems that I originally found and needed recharged. That is when it became difficult and confusing.
I had loaned my gauge set to a "friend" a while back and somehow he managed to get pieces of o-ring seals jammed down inside the hoses which had them almost totally plugged. As a result, the pressure readings that I was getting was from the hoses and not actually what was in the unit itself.
As soon as I get a chance to pick up a new manifold set, I will know more.
Thank You for your help.