Sequence of Operation LGM/LCM210, 240U, 300U
1 - Line voltage from TB13 energizes transformer T1 and T18. Transformer T1 and T18 provides 24VAC power to the main controller A55. The transformers also
provide 24VAC power to the unit cooling, heating and blower controls and thermostat.
ECONOMIZER OPERATION
2 -
3 -
1ST STAGE COOLING
4 - First stage cooling demand energizes Y1 and G in the thermostat.
5 - 24VAC is routed to the A55 Unit Controller. After A55 proves N.C. low pressure switch S87, and S88 and N.C. high pressure switch S4 and S7, high
temperature limits S5 compressor contactors K1 and K2 are energized.
N.O. contacts K1-1 and K2-1 close energizing compressor B1 and B2. Crankcase heater HR 2 is de-energized.
7 - A55 energizeS outdoor fans B4, B5 and B21. A178 energizes outdoor fan B22, B23 and B24.
8 -
2ND STAGE COOLING
Second stage cooling demand energizes Y2.
10 - N.O. contacts K14-1 close energizing compressor B13, de-energizing HR5.
11 -
BLOWER OPERATION With By Pass
1 -
2 - K203-1 N.C. contacts open to de-energize K3 relay coil. K3 contacts open to interrupt power to B3 blower motor through K3 N.O. relay contacts.
3 -
BLOWER OPERATION No By-Pass
1 -
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