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C−TD1−1 Time Delay (Early Models)
Some early model HS26 units are equipped with a Lennox−
built TD1−1 time delay located in the control box (figure 5).
The time delay is electrically connected between thermostat
terminal Y and the compressor contactor. On initial thermo
stat 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 satisfied, the time
delay opens the circuit to the compressor 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 compressor. A
scroll compressor, when short cycled, can run backward if
head pressure is still high. It does not harm a scroll com
pressor to run backward, but it could cause a nuisance trip
of safety limits (internal overload). For this reason, if a
TD1−1 delay should fail, it must be replaced. Do not bypass
the control.
D−TOC Timed Off Control
(Early and Late Models)
Some early and all late model HS26 units are equipped with
a TOC, timed off control.The TOC is located in the control
box (figure 6). The time delay is electrically connected be
tween thermostat terminal Y and the compressor contactor.
Between cycles, the compressor contactor is delayed for 5
m 2 minutes. At the end of the delay, the compres
sor is allowed to energize. When thermostat demand is sat
isfied, the time delay opens the circuit to the compressor
contactor coil and the compressor is de−energized. Without
the time 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 nui
sance tripout of safety limits. For this reason, if a TOC fails it
must be replaced.
DANGER
DO NOT ATTEMPT TO REPAIR THE TD1−1 OR THE
TOC CONTROL. UNSAFE OPERATION WILL RE
SULT. IF THE CONTROL IS FOUND TO BE INOP
ERATIVE, SIMPLY REPLACE IT.
FIGURE 5
HS26 UNIT COMPONENTS (EARLY MODEL)
CONTACTOR
LIQUID LINE
SERVICE VALVE
SUCTION
VALVE
COMPRESSOR
COMPRESSOR
TERMINAL BOX
THERMOMETER
WELL
DUAL CAPACITOR
AND GAUGE PORT
AND GAUGE PORT
LOW PRES
SURE SWITCH
COMPRESSOR
TEMPERATURE
SENSOR
CONDENSER FAN
(NOT SHOWN)
TOP OF CABINET
ACCUMULATOR
(411, 461 only
all others equipped
with suction muffler)
HIGH
PRESSURE
SWITCH
TD−1 TIME DELAY
OR T.O.C. TIMED OFF
CONTROL
