Two Central A/C questions

Commercial sheet metal guy some 30 years ago . I currently rent a condo built in the 70's with central A/C that was replaced two summers ago .

First question : we just called the installer for service , wasnt cooling well , the cleaned the condenser coils , and added a charge of refrigerant, working fine now . Why would it need a charge , they did replace the coolant lines when the did it two years ago . Is this something new with the newer R410 coolant ? or is there most likely a leak , the tech told my wife it would need an occasional charge .
Second ; the unit is in a small alcove with the return air pulling from a storge closet , and the only opening to the closet bifold doors is a small cat door. Return air grill is '24 x "14 , and the cat door is "12 x "8 , should there not be a much larger opening , like louvered bi fold doors . I would think the A/C is not getting enough return air .

 

You should not need annual re-charges, they tried that with my mom's new unit and we had another service come out and they found the leak.

I threated to sue and got a couple years worth of "repairs" refunded.

 

If you are renting this is something for the landlord to fix. That is what your rent pays for.

I agree. You should have zero coolant leakage. Even an old unit, with the cost of refrigerant, you do not want to regularly add refrigerant. There is a leak that needs to be found and fixed. The unit should be under warranty in case it's in a coil or plumbing internal to the unit and the installer should take care of any problem with the lines.