ActronAir Discharge Temperature Thermostat (R22 Compressor) monitors compressor discharge line temperature on R22 Classic Series systems, cutting power to the compressor if discharge temperature exceeds the safe operating limit to prevent compressor overheating damage in high-load or restricted-airflow conditions. Unlike pressure switches, this thermostat responds to thermal load rather than refrigerant pressure -- a blocked condenser or failed outdoor fan will trigger this protection before the high-pressure switch activates. Isolate power and recover refrigerant before replacing any compressor protection components.