Single-Phase Starting Sequence - Lennox HP21 Unit Information

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C−SINGLE-PHASE STARTING SEQUENCE
1− Line voltage feeds through L1 and L2 to energize outdoor transformer
T19 and outdoor unit. Crankcase heater is energized through relay K1
auxiliary contacts.
2− Transformer T19 provides 24VAC to TSC and contactors K1 and K69.
3− The indoor transformer supplies 24VAC to the indoor unit and the in-
door thermostat. Indoor transformer also provides 24VAC power to
FIGURE 28
defrost control CMC1, reversing valve L1, speed control thermostat
S55, service light thermostat S54 and ambient thermistor RT3 in out-
door unit.
4− On power-up, 24VAC is fed through JP44-1 and JP44-7 to the TSC.
The TSC begins a 10 second power-up delay.
5− The TSC begins a 5 minute delay during which the outdoor unit is not
operational. After the 5 minute delay, the TSC waits in OFF" mode for
1st stage or 2nd stage demand.
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