Oversized Air-Conditioning Compressor

It "short cycles" (starts and stops a lot). Poorer temperature control. Larger starting current, as well as maybe larger wiring, circuit breakers, etc. Costs more. Weighs more (maybe needs heavier structure). Not green (consumes/wastes more resources).

Thanks for the info, it is much appreciated

You have to understand the difference between oversized and a factor of safety terms. FOS is used generally in all design calculations as pert the relevant standards.