There are many reasons why an a/c unit will not cool.. Some are:
Low refrigerant, Dirty coils (evaporator and/or condensor), defective thermostat, defective valves in the compressor, dirty filter, defective fan, electrical problem, bad reversing valve (heat pump),etc. It appears that your maintence man has limited knowledge of air conditioning and did not perform a complete checkout of your unit.
Regards,
Dectech
