A simple refrigerant pipe leak undetected for a short period can cause loss of refrigerant, equipment failure or even compressor failure.
A simple loose wire connection undetected can cause sparks, fire, blowing of fuses, or even at times premature equipment failure.
Studies show that Heating and Cooling units on retail facilities run approximately 2000 hr/yr. This is equivalent of driving a car 60,000 miles per year.
A Preventive Maintenance program is basically like changing the oil in your car per the manufacturer's recommendation.