Do ask them to flush the condenser also, by properly dismantling that. And to change the drier filter which sits there next to condenser. That is important as it might have got all black by absorbing impurities. This drier filter helps removing impurities from the gas and keeps the condenser and AC system lighter by removing unwanted particles infused there. This will also help removing odour from the AC air.
If they have not opened up the compressor, its fine, just ask them to clean away dirt, gunk and greases from its surface, it will help in radiating heat properly and keeps the compressor temperature under control.
Do ask them to:
Properly flush the whole AC system, condenser, lines and pipes and change the Drier Filter (the one next to the condenser).
Clear the cooling oil evaporator and fit in the rings nicely.
Properly vacuum the system after assembling (if not vacuum, the system will not cool effectively).
Do proper oiling, with proper amount of oil in the compressor (he can use the same vacuum to suck in the oil)
Make the blower assembly (internally) just like a new one. Clean and clear.
Fill in the Gas then.
After, filling the Gas, in day time drive a little bit so (5-10 mins). Then check the sight-glass in the engine cabin. There should be no bubble and a very clear view there, if NOT then ask them to check the Gas pressure using their meter again.
Above things will make you AC system like new again.
All this, if you ask me is not more than a 2-3 hours job if handled efficiently.