A relay rated for motor loads that connects line voltage to the compressor and condenser fan.
A 24 V coil pulls the contactor in when the thermostat calls (through Y and any safeties in series). If there is 24 V across the coil and the contactor does not pull in, the coil or the mechanism has failed. If there is no 24 V, trace the control circuit back through pressure switches, float switches and time delays to the thermostat. Pitted contacts cause voltage drop and heat.
Exam work areas
F · Maintenance, service and troubleshooting