The evaporator has a temperature sensor (aka thermistor) to tell the climate control module the temperature of the evaporator. Typically, the climate control module won't energize the compressor is the evaporator temperature is much below 40*F. When it's hot outside and the AC is running the...
You need to consider how the car is driven. Stop and go driving is harder on the car in general than highway driving. My wife's ancient Accord is driven mainly on short trips. I drain and refill 3 quarts of the automatic transmission fluid yearly.
Try using DMSO (Dimethyl sulfoxide) in the oil. Here's how: