aircon

[UKZR1]

Help!!
Before I pulled the engine and shipped it to the states the aircon worked just fine. So I was a bit surprised when I went to have it re-gassed that it had a problem.
I watched as they measured out and put in new dye and oil and then new gas.
It was then that the engine was started, loads of noise from the compressor, low side pressure went too high and talk of a blockage. The inline filter was changed (there were some metal fragments on it) and they tried again.
Again the compressor sounded like a bag of bolts, cold air was blowing for a very short time then turned warm and the low side pressure went high again. Garage suspected the compressor.
I pulled the plenum and took the compressor to a place for testing. I have just heard back from them and it passed all tests fine.
I must have a blockage? everything was plugged while the engine was in the states.
Any suggestions on what to do next??