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When thermostat calls for Stage 2 Cooling, terminal Y2 is
energized. The 575J unit's Defrost Board (DFB) receives this
input at P2-4. DFB issues 24-v outputs at OF, P3-8 (COMP2).
Output PL3-8 (COMP2, 24-v) is received at CADM terminal
Y2. CADM DC SOL terminal outputs 24-vdc to the compres-
sor loader plug (LDR) and the compressor operates at full load
capacity.
As space cooling load is satisfied, thermostat outputs Y2 and
Y1 are sequentially de-energized, removing 24-v at terminals
Y2 and Y1. Compressor Loader plug is de-energized on Y2
opening. On Y1 opening, the Compressor stops, all outdoor fan
motors stop and SVR relay is de-energized. Liquid line sole-
noid valve is de-energized and valve closes. CADM begins its
three-minute anti-recycle time delay.
If either the Loss of Charge (LOC) Switch or High Pressure
Switch (HPS) opens while Y1 remains energized, the compres-
sor contactor C and relay SVR are de-energized; compressor
stops and liquid line solenoid is de-energized (valve closes).
CADM initiates a TRIP event (cooling demand sensed at
CADM terminal Y but no current is measured at T1, T2, T3
motor sensors); CADM relay opens and RED LED is illumi-
nated. TRIP condition maintains lockout of compressor opera-
tion until CADM is manually reset. Reset CADM by cycling
unit main power. Reversing valve solenoid (RVS) is energized
in Cooling modes. This solenoid will remain energized until
the next Heating mode is initiated.
575J*12G/H
When thermostat calls for Stage 1 Cooling, terminal Y1 is en-
ergized. The 575J unit's Defrost Board (DFB) receives this in-
put at P2-5. DFB issues 24-v outputs at OF, P3-7 (RVS1) and
P3-10 (COMP1). The OF output energizes outdoor fan relay
(OFR); both outdoor fan motors start and run. The output
RVS1 energizes the reversing valve solenoid (RVS); Reversing
valve switches to Cooling position. Output PL3-10 (COMP1,
24-v) is received at CADM1 terminal Y. If anti-recycle time
delay period has not expired, safety pressure switches are open,
and/or lockout alarms are active, CADM1 relay will remain
open, preventing compressor start. When safety pressure
switches are closed and CADM time delay expires, the
CADM1 relay closes, energizing Solenoid Valve Relay SVR
and compressor contactor C1. SVR contacts close, energizing
the external liquid line solenoid valve.Solenoid valve LLSV
opens. Compressor contactor C1closes, energizing the com-
pressor motor. Compressor A1starts and system runs in Stage 1
Cooling mode.
When thermostat calls for Stage 2 Cooling, terminal Y2 is en-
ergized. The 575J unit's Defrost Board (DFB) receives this in-
put at P2-4. DFB issues 24-v outputs at OF, P3-8 (COMP2).
Output PL3-8 (COMP2, 24-v) is received at CADM2 terminal
Y. If anti-recycle time delay period has not expired and/or lock-
out alarms are active, CADM2 relay will remain open, prevent-
ing compressor start. When CADM2 time delay expires, the
CADM2 relay closes, energizing compressor contactor C2.
Compressor contactor C2 closes, energizing the compressor
motor. Compressor A2 starts and system runs in Stage 2 Cool-
ing mode.
As space cooling load is satisfied, thermostat outputs Y2 and
Y1 are sequentially de-energized, removing 24-v at terminals
Y2 and Y1. Compressor A2 is de-energized on Y2 opening. On
Y1 opening, Compressor A1 stops, all outdoor fan motors stop
and SVR relay is de-energized. Liquid line solenoid valve is
de-energized and valve closes. CADM begins its three-minute
anti-recycle time delay.
If either the Loss of Charge (LOC) Switch or High Pressure
Switch (HPS) opens while Y1 remains energized, the compres-
sor contactor C and relay SVR are de-energized; compressor
stops and liquid line solenoid is deenergized (valve closes).
CADM initiates a TRIP event (cooling demand sensed at
CADM terminal Y but no current is measured at T1, T2, T3
motor sensors); CADM relay opens and RED LED is illumi-
nated. TRIP condition maintains lockout of compressor
operation until CADM is manually reset. Reset CADM by cy-
cling unit main power. Reversing valve solenoid (RVS) is ener-
gized in Cooling modes. This solenoid will remain energized
until the next Heating mode is initiated.
FAN CYCLING
The 575J*12G/H is equipped with a temperature switch that
will shut down one outdoor fan in cooling mode when the out-
door temperature falls below 55°F (13°C) to ensure continuous
operation in both stages. The outdoor fan will turn back on
when the temperature rises above 60°F (16°C).
COOLING, UNIT WITH ECONOMIZER
Refer to fan coil unit installation instructions and economizer
accessory installation instructions for operating sequences
when system is equipped with accessory economizer.
HEATING
When the thermostat calls for first stage heating, terminal W1
is energized. The 575J unit's Defrost Board (DFB) receives
this input at P2-7. The DFB removes the output at P3-7
(RVS1); the reversing valve solenoid is de-energized and the
reversing valve moves to Heating position.
DFB issues outputs at OF and P3-10 (COMP1). Outdoor fan
relay OFR is energized; both outdoor fan motors run.
Output PL3-10 (COMP1, 24-v) is received at CADM terminal
Y. If anti-recycle time delay period has not expired, safety
pressure switches are open, and/or lockout alarms are active,
CADM relay will remain open, preventing compressor start.
When safety pressure switches are closed and CADM time de-
lay expires, the CADM relay closes, energizing Solenoid Valve
Relay SVR and compressor contactor C. SVR contacts close,
energizing the external liquid line solenoid valve. Solenoid
valve LLSV opens. Compressor contactor C closes, energizing
the compressor motor. Compressor starts and system runs in
Heating mode, providing Stage 1 Heat.
When the space heating load is satisfied terminal W1 is de-
energized. Compressor and outdoor fan operations stop. Liquid
line solenoid LLSV is de-energized and valve closes. CADM
begins its three-minute anti-recycle time delay.
If either the Loss of Charge (LOC) Switch or High Pressure
Switch (HPS) opens while, the compressor contactor C and re-
lay SVR are de-energized; compressor stops and liquid line so-
lenoid is de-energized (valve closes). CADM initiates a TRIP
event (compressor demand sensed at CADM terminal Y but no
current is measured at T1, T2, T3 motor sensors); CADM relay
opens and RED LED is illuminated. TRIP condition maintains
lockout of compressor operation until CADM is manually re-
set. Reset CADM by cycling unit main power.
Reversing valve solenoid remains de-energized until the next
Cooling cycle is initiated.
DEFROST CYCLE
During the Heating Mode, frost and ice can develop on the out-
door coil. Defrost sequence will clear the frost and ice from the
coil by briefly reversing the Heating sequence periodically.
A window to test for a need to run the Defrost cycle opens at a
fixed period after the end of the last Defrost cycle or the previ-
ous test window closed. The window period is determined by
the configuration settings on the DFB's DIP switches (see unit
wiring diagram).
If the outdoor coil's Defrost Thermostat switch (DFT) is closed
(shorting DFB terminals DFT1 and DFT1), the Defrost cycle
will start. Output at OF is removed; outdoor fans stop during
the Defrost cycle. Output P-7 (RVS1) is energized; reversing
valve solenoid RVS is energized and reversing valve changes
position, placing the circuit in a Cooling mode flow, directing
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