Lennox Signature XP21 Series Installation And Service Procedure page 78

Y1 DEMAND
SWITCH (S4)
COMPRESSOR
CONTACTOR
DE−ENERGIZED
OPEN
COMPRESSOR
ANTI−SHORT
CYCLE TIMER
ANTI−SHORT
CYCLE TIMER
COMPRESSOR
CONTACTOR
ENERGIZED
SWITCH (S4)
SERVICE
2
REQUIRED
WAITING FOR
OPEN
Figure 44. High Pressure Switch (S4) Sequence of Operation (All Versions)
XP21
HIGH
PRESSURE
CLOSED
HIGH
PRESSURE
OPEN
SWITCH (S4)
1
If 5−strike counter has four or less strikes when Y1 demand
is terminated or satisfied, the strike counter will reset to
zero. In a icomfortt setup, the thermostat will terminate
demand when the compressor contactor is de−energized. If
demand is satisfied when alarm is not active, the 5−strike
counter will reset.
2
Lockouts can be reset by either cycling power off to the
BEGINS
heat pump control's (A175) R terminal, or placing a jumper
on the field test pins (E33) between 1 to 2 seconds.
INCREMENT
5−STRIKE
1
COUNTER
LED ALERT
CODE / OR
MODERATE
ALERT 412
DISPLAYED
ENDS
HIGH
PRESSURE
CLOSED
PRESSURE
CLOSED
SWITCH TO
CLOSE
COMPRESSOR
CONTACTOR
ENERGIZED
CLOSED
5−STRIKE
COUNTER
REACHES 5
WITHIN A SINGLE
Y1 DEMAND
HIGH
PRESSURE
SWITCH (S4)
LOCKOUT
LED ALERT
CODE / OR
CRITICAL
ALERT 413
CLEARED
LED ALERT
CODE / OR
MODERATE
ALERT 412
DISPLAYED
Page 78
SERVICE
2
REQUIRED
NORMAL
OPERATION