In my humble opinion, the cleaning is a great idea. I agree with you that the receiver / dryer (drier?) needs to be replaced, that is routine anytime the system is opened up. I'll bet that a new expansion valve is also in order, and the compressor is suspect if it has been pumping trash from a previous compressor failure.

What I fail to understand is why you are looking for a new tech. Would you have preferred that he simply replace components before charging it to test it? How was he (or anyone) to know there was a blockage? It seems that if the system was performing before you brought it in, he made an assumption that the compressor and maybe the expansion valve were good, and a simple/cheap first step is to evacuate the system, then check for leaks, then charge the system and test performance.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC