©2025 Copeland LP.
026-1803 R13 Supervisor I&O User Guide A - 6
Proof Fail
Device
Alarm
T-Stat
Fan Not Detected – Any time, when the fan is activated and if
the Fan Detect input is enabled, the Thermostat shall check its
status 15 seconds after the fan is energized, and if the fan is not
on, it shall disable any active heat or cool calls, and report an
alarm.
Frost
Protection
Activated
Device
Alarm
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 disabled, and indoor heat is activated
until the temperature rises above the frost protection threshold.
Long Run
Time
Device
Alarm
T-Stat
Compressor is running extremely long run cycles (typically for
over 18 hours). The possible causes are: Low refrigerant
charge, Evaporator blower is not running, Evaporator coil is
frozen, Faulty metering device, Condenser coil is dirty,
Thermostat is malfunctioning, Compressor Second Stage
Cooling Wiring.
System
Pressure Trip
Device
Alarm
T-Stat
Discharge or pressure out of limits or compressor overloaded.
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
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
T-Stat
Locked rotor. The possible causes are: Run capacitor has failed,
Low line voltage, Excessive liquid refrigerant in compressor,
Compressor bearings are seized.
Open Circuit
Device
Alarm
T-Stat
Compressor open circuit. The possible causes are: Outdoor unit
power disconnect is open, Compressor circuit breaker or
fuse(s) is open, Compressor contactor has failed open, High
pressure switch is open and requires manual reset, Open circuit
in compressor supply wiring or connections, Unusually long
compressor protector reset time due to extreme ambient
temperature, Compressor windings are damaged.
Open Start
Circuit
Device
Alarm
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
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
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
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).
Alarm Items Category Cell Name Description
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