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HP23 THREE PHASE OPERATING SEQUENCE
A–HP23 P Voltage Operation Sequence
This is the sequence of operation for HP23 “Y”, “G”,
and “J” voltage units. The sequence is outlined by
numbered steps which correspond to circled num-
bers on the adjacent diagram.
NOTE– The thermostat used may be electrome-
chanical or electronic.
NOTE– Transformer in indoor unit supplies power (24
VAC) to the thermostat and outdoor unit controls.
COOLING:
1 – Cooling demand initiates at Y1 in the thermostat.
Internal thermostat wiring energizes terminal O
energizing the reversing valve L1.
2 – 24VAC energizes compressor contactor K1.
3 – K1-1 N.O. closes energizing compressor (B1) and
outdoor fan motor (B4).
4 – Compressor (B1) and outdoor fan motor (B4)
begin immediate operation.
END OF COOLING DEMAND:
5 – Cooling demand is satisfied. Terminal Y1 is
de-energized.
6 – Thermostat terminal O is de-energized.
7 – Reversing valve L1 is de-energized
8 – Compressor contactor K1 is de-energized.
9 – K1-1 opens and compressor (B1) and outdoor
fan motor (B4) are de-energized and stop im-
mediately.
FIRST STAGE HEAT:
10 – Heating demand initiates at W1 in the ther-
mostat.
11 – 24VAC energizes compressor contactor K1.
12 – K1-1 N.O. closes energizing compressor
and outdoor fan motor.
13 – Compressor (B1) and outdoor fan motor (B4)
begin immediate operation.
END OF FIRST STAGE HEAT:
14 – Heating demand is satisfied. Terminal W1 is
de-energized.
15 – Compressor contactor K1 is de-energized.
16 – K1-1 opens and compressor (B1) and outdoor
fan motor (B4) are de-energized and stop im-
mediately.
DEFROST MODE:
17 – During heating operation when outdoor coil
temperature drops below 35
+ 4
F Defrost
Switch (thermostat) S6 closes.
18 – Defrost control CMC1 begins timing. If defrost
thermostat (S6) remains closed at the end of
the 30,60 or 90 minute period, defrost relay K4
energizes and defrost begins.
19 – N.O. K4-3 closes energizing the reversing valve.
20 – N.O. K4-1 closes energizing W1 on TB1 terminal
strip of indoor unit. Indoor unit operates in the
first stage heat mode.
21 – N.C. K4-2 opens and outdoor fan motor B4 stops.
22 – Defrost continues 14 + 1 minutes or until ther-
mostat switch (S6) opens. When defrost ther-
mostat opens defrost control CMC1 loses
power and resets.
23 – Defrost relay K4 is de-energized.
24 – K4-1 opens and W1 on terminal strip TB1 of
indoor unit is de-energized.
25 – K4-2 closes and the outdoor fan begins operation.
26 – K4-3 opens de-energizing the reversing valve.
