How to reset the A/C compressor?

Need to know - when you take a car your car in for a/c repairs - is it standard practice to leak test the system before doing any work?

I took my caddy in cause a/c had quit working. Compressor was noisy and had a burnt bearing smell. Clearly there was a problem with compressor and it was changed. Morning after I took car home I heard a soft hiss under the dash and then a soft "pop" and a cloud of freon(?) Come up from the right side of the engine (hood was open to jump car). Took car back and was told I had an evaporator leak.

Called another mechanic who said system should've been leak tested before compressor work was done. Said he always does this as compressor went out for a reason and no sense replacing compressor if there's a bigger problem, etc.

I told my mechanic this and he said he couldn't leak test system with shot compressor. I think he could've - but I don't know.

Short/long - 2 quesitons:

(1) Is it standard practive to leak test a/c systems before doing repairs, and

(2) Can you leak test an a/c system with a shot compressor?

Thanks for feedback. Clarification please?

(1) My mechanic told me when I picked up the car that he'd put a green dye in the freon so he could see leaking with a black light - if I had a leak. He said he thought I might have a leak - since compressor went out and no freon in system when he went to do repairs. He told me to drive the car for a few days and then bring it back it so he could give it a once over for leaks.

(2) The morning after I brought it home I started it and that's when I heard the soft hiss under the dash and then hiss/pop/cloud of freon (?) On right side of engine. Cloud of vapor was not green - so not sure about the green dye claim he made.

(3) Having said all that - I have 4 questions:

(A) If you were given a car with a noisy compressor to fix - would you have evacuated the system/noted leaks and not gone any further until leak situation had been discussed?

(B) Since a/c was blowing cool (not cold) right before it quit and I smelled burned bearings - is it likely that freon leaked out slowly and a/c was able to still blow cool right up to the time the compressor crapped out?

(C) Hissing sound ("soft" sounding - but still noticeable) under the dash never occurred before. The morning after I brought car home was first time I heard. Could the mechanic, while repairing the compressor/charging the system, overcharge the system/pop a seal? Only reason I ask is I never heard the hiss before and his voicing a concern about a system leak/coming back to me telling me for sure evaporator has a leak after I took car back makes me wonder if he did something to cause hiss/leak to occur. Thoughts?

(4) Since Caddy's not worth much - would this be a good time to try CryoSeal?

(1) If you were given a car with a noisy compressor to work on - would you evacuate the lines/put system on a vacuum/note if vacuum held before proceeding to replace compressor?

(2) Since car is now hissing/popping/releasing a cloud of vapor on the driver side of the engine when it runs (compressor is on passenger side) - could it be that the orifice wasn't replaced/is clogged and/or something other than a leak in the evaporator is causing the hiss/pop/vapor under the hood?

Adding R-134. Compressor will not engage or cycle.

(1) Compressor was making noise - i.E. It was turning but I think innards were shot. May not have been able to test for leaks in this condition?

(2) On the noise/vapor - Hiss/pop/vapor release happened when I started car up morning after I brought it home from mechanic. It happened twice. One hiss/pop/vapor release then a second hiss/softer pop/much smaller release of vapor.

Insofar as the hiss/pop/vapor on driver side when compressor's on passenger side issue goes - any ideas?

P.S. - My bad on using right side. I meant the issue's on the right side of the engine if you're standing in front of the car. Figured it would be better to start talking like a mechanic - i.E. Use driver/passengerr side instead of left/right.

Thanks for input so far. Need some clarification so gonna ask questions a little different/provide some add'l info along with so I can stop bothering you :)

(1) If someone brought you a car with a noisy compressor and, as you proceeded to evacuate the freon you found no freon in the system - would you assume the system had a leak and leak test the system before you did the compressor replacement as a matter of course?

(2) If after replacing the compressor you sent the car home and your customer came back next day telling you he'd heard a hiss/pop under the hood and saw a puff of vapor come up on the driver side of the engine halfway between the radiator and the firewall - would you suspect there was a problem with the compressor you'd just installed or what?

Overheat compressor off fan don'ts work

10-4. But the compressor wasn't running when I took car to shop. A/C had stopped running and I smelt a burned metal smell so I never re-engaged the a/c. I just took car to shop and, with just the engine running - there was noise coming from the compressor and the mechanic said I needed a new compressor.

All I'm asking is this:

Before he yanked the compressor - should he not have evacuated the system and in so doing discovered the leak in the evaporator (which is what he now says I have and what he now says caused the a/c system to lose freon and compressor to fail)?

What can I do to resolve compressor fans over heat problem