Portable Air Conditioner Compressor Never Cycles On & Off - Is this normal?
There is no problem with the unit running continuously without a break. The most wear occurs when the compressor starts up from being off. A unit that is sized to run continuously is actually more efficient than one that cycles on and off.

We have a slightly undersized Carrier central a/c unit (12 SEER) which is 26 years old, but still works as well as could be expected for one that age. The blower fan motor is original and the compressor is original. The original fan in the condensing unit failed and was replaced 2 years ago. On very hot summer days (>100 F) it turns on at say 11:00 am and runs continuously until 5 pm.