Y1 DEMAND
OR COOLING
PRESSURE ABOVE
DEMAND
CONTACTOR
DE-ENERGIZED
NO
PRESSURE ABOVE
SERVICE
2
REQUIRED
NO
TO RISE ABOVE
Figure 30. Low Pressure Switch Emulated by Suction Pressure Transducer Sequence of Operation (All Units)
*SUCTION
YES
CUT-OUT OF
40 PSIG
SUCTION PRESSURE
ABOVE CUT-OUT
NO
OF 40 PSIG
1.
The thermostat terminates demand when the contactor
is de-energized. If demand is satisfied when alarm is
not active, the 5-strike counter resets.
2.
ANTI-SHORT
door control (A175) R terminal.
CYCLE TIMER
The suction pressure cut-out of 40 psig is ignored by the
3.
BEGINS
system when the outdoor temperature is below 15°F.
INCREMENT
5-STRIKE
WITHIN A SINGLE
1
COUNTER
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
ANTI-SHORT
CYCLE TIMER
ENDS
CONTACTOR
ENERGIZED
SUCTION
YES
CUT-IN OF
90 PSIG
WAITING FOR
PRESSURE
YES
90 PSIG
NO
CONTACTOR
ENERGIZED
YES
5-STRIKE
COUNTER
REACHES 5
Y1 DEMAND
LOW
PRESSURE
LOCKOUT
LED ALERT
CODE / OR
SERVICE
CRITICAL
REQUIRED
ALERT 411
DISPLAYED
LED ALERT
CODE / OR
MODERATE
ALERT 410
DISPLAYED
*Unit does not have a low pressure switch
and LPS terminals are not jumpered. The
unit has a suction pressure transducer that
emulates the low pressure switch with a
cut-out of 40 PSIG and a cut-in of 90 PSIG.
Page 60
SUCTION
PRESSURE
CUT-OUT IS
IGNORED FOR
90 SECONDS
SUCTION PRESSURE CUT-OUT
IS BYPASSED IF OUTDOOR
AMBIENT TEMPERATURE IS 15ºF
3
OR BELOW
2
NORMAL
OPERATION
31-5000746 Rev. 0