Sorry don't know if mine is R134 or R12 but just had the condenser and dryer replaced because of a leak. Prior to that when the system was properly filled and pressurized I would get decent cooling, but got tired of refilling.
Anyway went for a drive today in 39C/102F temp (70% humidity) and with the fan speed at "2" I was ok, but turned it up to "3" while in the sun. I beleive the aircon works more effeciently at higher humidity like ours, though. I would describe it as adequate, but not as cold as my other cars.

 

If I understood well, the dryer, the condenser and the expansion valve are easy to replace, at least when compared to the evaporator.

The question is whether their replacement, given a pre-existing non-leaking system, has a chance to improve performance.

Any experience/advice welcome

Phil