A-6 • Site Supervisor Controller User Guide 2.0 026-1800 Rev 3 02-AUG-2016
Frost Protection Activated Device Alarm Emerson T-Stat The thermostat shall allow a frost protection menu
option. When enabled, frost protection is enabled in all
system modes including OFF, when temperature drops
below 42 °F (5.6 °C). All other heat / cool calls are dis-
abled, and indoor heat is activated until the tempera-
ture rises above the frost protection threshold.
Long Run Time Device Alarm Emerson T-Stat Compressor is running extremely long run cycles (typ-
ically for over 18 hours). The possible causes are: Low
refrigerant charge, Evaporator blower is not running,
Evaporator coil is frozen, Faulty metering device, Con-
denser coil is dirty, Thermostat is malfunctioning,
Compressor Second Stage Cooling Wiring.
System Pressure Trip Device Alarm Emerson T-Stat Discharge or pressure out of limits or compressor over-
loaded. The possible causes are: High head pressure,
Condenser coil poor air circulation (dirty, blocked,
damaged), Condenser fan is not running, Return air
duct has substantial leakage.
Short Cycling Device Alarm Emerson T-Stat Compressor is running only briefly. The possible
causes are: Thermostat demand signal is intermittent,
Time delay relay or control board is defective, High
pressure switch present.
Locked Rotor Device Alarm Emerson T-Stat Locked rotor. The possible causes are: Run capacitor
has failed, Low line voltage, Excessive liquid refriger-
ant in compressor, Compressor bearings are seized.
Open Circuit Device Alarm Emerson T-Stat Compressor open circuit. The possible causes are: Out-
door unit power disconnect is open, Compressor cir-
cuit breaker or fuse(s) is open, Compressor contactor
has failed open, High pressure switch is open and
requires manual reset, Open circuit in compressor sup-
ply wiring or connections, Unusually long compressor
protector reset time due to extreme ambient tempera-
ture, Compressor windings are damaged.
Open Start Circuit Device Alarm Emerson T-Stat Compressor current only in run circuit. The possible
causes are: Run capacitor has failed, Open circuit in
compressor start wiring or connections, Compressor
start winding is damaged.
Open Run Circuit Device Alarm Emerson T-Stat Compressor current only in start circuit. The possible
causes are: Open circuit in compressor run wiring or
connections, Compressor run winding is damaged.
Welded Contactor Device Alarm Emerson T-Stat Compressor always runs. The possible causes are:
Compressor contactor has failed closed, Thermostat
demand signal is not connected to module.
Low Voltage Device Alarm Emerson T-Stat Control circuit < 17VAC. The possible causes are:
Control circuit transformer is overloaded, Low line
voltage (contact utility if voltage at disconnect is low).
Protector Trip Device Alarm Emerson T-Stat Thermostat demand signal Y is present, but the com-
pressor is not running. The possible causes are: Com-
pressor protector is open, Outdoor unit power
disconnect is open, Compressor circuit breaker or
fuse(s) is open, Broken wire or connector is not mak-
ing contact, High pressure switch open if present in
system, Compressor contactor has failed open.
Alarm Items Category Cell Name Description
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