Hp21−36−230 / 60−230−3 Units Operation Sequence - Lennox HP21 Unit Information

SINGLE-PHASE COOLING SEQUENCE
The TSC two−speed control has an external temperature probe
to lockout low speed during low temperatures, plus a poten-
tiometer used for setting the low speed lock out temperature.
The adjustment range is 38° to 55°. This lockout will occur in
heating and cooling mode.
1− 1st stage cooling demand energizes TB15-Y1 and TB15-O.
TB15-O sends signal to O on defrost board which energizes
reversing valve L1. TB15-Y1 energizes TSC terminal
JP44-6.
NOTE-2nd stage cooling demand may be energized direct-
ly without passing through 1st stage.
2− TSC delays 3 seconds before responding to the new com-
mand.
3− If the unit is changing from 2nd stage to 1st stage demand,
TSC initiates speed change delay and de-energizes JP44-8
and JP44-9 to stop all unit operation for 60+5 seconds. After
TSC completes the 60+5 second speed change delay or if
the unit is starting-up in 1st stage directly from OFF mode,
TSC checks safety circuits by looking for 24VAC at JP44-7
and by checking resistance through wires connected to S1
and S2.
4− If all safety circuits check-out, TSC energizes K1 and com-
pressor begins low speed startup.
5− 2nd stage cooling demand energizes TB15-Y1, TB15-Y2
and TB15-O. TB15-Y2 energizes TSC terminal JP44-4.
TB15-Y1 energizes TSC terminal JP44-6.
6− TSC delays 3 seconds before responding.
7− If the unit is changing from 1st stage to 2nd stage demand,
the TSC initiates speed change delay and de-energizes
JP44-8 and JP44-9 to stop all unit operation for 60+5 sec-
onds. After TSC completes the 60+5 second speed change
delay or if the unit is starting-up in 2nd stage directly from
OFF mode, TSC checks safety circuits by looking for 24VAC
at JP44-7 and by checking resistance through wires con-
nected to S1 and S2.
8− If all safety circuits check-out, TSC energizes K1 and K69.
Compressor begins high speed startup.
9− When thermostat demand is satisfied or if thermostat is
switched OFF or switched to heating mode, all outdoor unit
operation stops after a delay of 3 seconds. TSC then com-
pletely resets (erase accumulated faults) before beginning a
5 minute timed-off delay.
HP21−36−230 / 60−230−3 UNITS
OPERATION SEQUENCE
SINGLE-PHASE HEATING SEQUENCE
10−1st stage demand energizes TB15-Y1. TB15-Y1 energizes
11− TSC delays 3 seconds before responding to the new com-
12− 2nd stage heating demand energizes TB15-Y1 and
DEFROST SEQUENCE
Upon initial power up or first heating demand after cooling
mode, a sacrificial" defrost operation will occur in order to cali-
brate the board. Calibration will occur after accumulated com-
pressor run time of 34 minutes and coil temperature is below
35°.
13− Y1 is energized in HEAT mode, de−energizing reversing
14− Compressor run time of 34 minutes accumulated. Defrost
15− Defrost will last a maximum of 14 minutes or until the coil
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TSC, and defrost control. Defrost control initializes timing
sequence.
NOTE-2nd stage heating demand may be energized di-
rectly without passing through 1st stage.
mand. Then compressor begins operating at low or high
speed depending on the outdoor ambient.
TB15-W1. TB15-Y1 energizes TSC. The compressor con-
tinues to operate at low or high speed as determined by the
outdoor ambient. W1 energizes the indoor auxiliary heat
relay for 2nd stage heat.
valve.
begins. N.C. FAN terminal on board remains open, allowing
fan to cycle during defrost.
temperature sensed at the coil probe exceeds the selected
pin termination temperature. Pin values are 50°, 60° 70° and
80°. (Factory setting is 70°).