Abstract: An electronic monitoring system is provided to monitor for and sense faults in a residential or commercial air conditioning system that uses a chemical refrigerant. By monitoring the discharge pressure variable, a determination may be made concerning the condition of the air conditioning system and alert the home owner or resident when the air conditioning system requires professional service. The early warning of system air conditioning system faults will give the property owner the opportunity to service the system before more long term damage is done to the system. The microprocessor based control will monitor the discharge line pressure and transmit a signal to a system monitor panel that is co-located with the heating/air conditioning thermostat installed within the dwelling or structure. A display on the face of the monitor panel will alert the home owner or resident, in an incremental manner, when the air conditioning system is in urgent need of professional service.