Page 4
III–UNIT COMPONENTS
A–Transformer
The contactor coil, time delay and temperature sen-
sor are all energized by 24VAC supplied by the indoor
unit. All other controls in the outdoor unit are pow-
ered by line voltage. Refer to unit wiring diagram.
The HS25 is not equipped with an internal line volt-
age to 24V transformer.
B–Contactor
The compressor is energized by a contactor located in
the control box. HS25-211 through -511 units use SPST
contactors. HS25-651 units use a DPST contactor. The
contactor is energized by indoor thermostat terminal Y
when thermostat demand is present.
WARNING
HS25 UNITS USING SINGLE-POLE CONTACTORS:
ONE LEG OF COMPRESSOR, CAPACITOR AND
CONDENSER FAN ARE CONNECTED TO LINE
VOLTAGE AT ALL TIMES. POTENTIAL EXISTS FOR
ELECTRICAL SHOCK RESULTING IN INJURY OR
DEATH. REMOVE ALL POWER AT DISCONNECT
BEFORE SERVICING.
C–TD1–1 Time Delay
Each HS25 is equipped with a Lennox built TD1–1 time
delay located in the control box (figure 4). The time
delay is electrically connected between thermostat ter-
minal Y and the compressor contactor. On initial ther-
mostat demand, the compressor contactor is delayed
for 8.5 seconds. At the end of the delay, the compressor
is allowed to energize. When thermostat demand is sa-
tisfied, the time delay opens the circuit to the compres-
sor contactor coil and the compressor is de–energized.
The time delay performs no other functions. Without
the delay it would be possible to short cycle the com-
pressor. A scroll compressor, when short cycled, can
run backward if head pressure is still high. It does not
harm a scroll compressor to run backward, but it could
cause a nuisance tripout of safety limits (internal over-
load). For this reason, if a TD1–1 delay should fail, it
must be replaced. Do not bypass the control.
DANGER
DO NOT ATTEMPT TO REPAIR THIS CONTROL.
UNSAFE OPERATION WILL RESULT. IF THE CON-
TROL IS FOUND TO BE INOPERATIVE, SIMPLY RE-
PLACE THE ENTIRE CONTROL.
FIGURE 4
HS25 UNIT COMPONENTS
CONTACTOR
LIQUID LINE
SERVICE VALVE
SUCTION LINE
SERVICE VALVE
COMPRESSOR
COMPRESSOR
TERMINAL BOX
THERMOMETER
WELL
DUAL CAPACITOR
TD1–1
TIME DELAY
AND GAUGE PORT
AND GAUGE PORT
LOW
PRESSURE
SWITCH
COMPRESSOR
TEMPERATURE
SENSOR
CONDENSER FAN
(NOT SHOWN)
TOP OF CABINET
ACCUMULATOR
HS25-511/651
ONLY
HIGH
PRESSURE
SWITCH
