Lennox XC20-036-230-01 Installation And Service Procedure page 52

Y1 DEMAND
CONTACTOR
DE-ENERGIZED
OPEN
SERVICE
2
REQUIRED
OPEN
Figure 29. High Pressure Switch (S4) Sequence of Operation (All Versions)
XC20
HIGH
PRESSURE
CLOSED
SWITCH (S4)
PRESSURE
OPEN
SWITCH (S4)
The thermostat terminates demand when the contactor is
1.
de-energized. If demand is satisfied when alarm is not active, the
5-strike counter resets.
Lockouts can be reset by cycling power off to the outdoor control
2.
ANTI-SHORT
(A175) R terminal.
CYCLE TIMER
BEGINS
INCREMENT
5-STRIKE
1
COUNTER
LED ALERT
CODE / OR
MODERATE
ALERT 412
DISPLAYED
ANTI-SHORT
CYCLE TIMER
ENDS
HIGH
PRESSURE
CLOSED
SWITCH (S4)
WAITING FOR
PRESSURE
CLOSED
SWITCH TO
CLOSE
TOP CAP
SWITCH (S173)
HIGH
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
52
CONTACTOR
CLOSED
ENERGIZED
SERVICE
2
REQUIRED
NORMAL
OPERATION