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KGB024/090 P, Y, G, J & M Voltage Sequence of Operation
Power:
1. Line voltage from unit disconnect energizes transformer T1. T1 provides 24VAC power to
terminal strip TB1. TB1 provides 24VAC to the unit cooling, heating and blower controls.
Blower Operation:
2. Indoor thermostat terminal G energizes blower contactor K3 with 24VAC.
3. N.O. K3 closes, energizing blower B3.
Economizer Operation:
4. The economizer control module receives a demand and energizes exhaust fan relay K65 with
24VAC at 50% outside air damper open (adjustable).
5. N.O. K65-1 and N.O. K65-2 both close, energizing exhaust fan motor B10.
Cooling Demand
6. First stage cooling demand Y1 and G is energized by the thermostat. G energizes blower.
7. 24VAC is routed through TB1 to N.C. freezestat S49, and optional N.C. high pressure switch
S4. Compressor contactor K1 is energized.
8. N.O. K1-1 close energizing compressor B1.
9. Single Phase P Voltage Units
Optional N.O. low ambient switch S11 closes to energize condenser fan B4.
Three Phase Y Voltage Units
Optional N.O. low ambient switch S11 closes to energize condenser fan B4.
Three Phase G, J & M Voltage Units
Optional N.O. low ambient switch S11 closes to energize condenser fan relay K10.
N.O. contacts K10-1 close energizing condenser fan B4 .
KGB-074 Two-Stage Units
10. First-stage cooling demand Y1 and G is energized by the thermostat. G energizes blower.
11. Following from step 7 K1 energizes compressor, condenser fan and blower B1 on low speed.
12. Second-stage cooling demand Y2 energizes compressor B1, condenser fan and blower B1 on
high speed.
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