you will have to find someone with guages and see what the pressures are running when blowing cold and hot also check to make sure your condenser fins are clean and straight, make sure your fan is kicking in if not excessive condenser temp/pressure could open the high pressure cut out switch, if you suspect this find a high cfm fan and stick it in front of your grille and see what happens, but again guage readings will be the most accurate way to diagnose