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The following safety features are provided to protect the
compressor, heat exchangers, wiring and other compo-
nents from damage caused by operation outside of design
conditions.
Anti-Short Cycle Protection
- The control features a 5
minute anti-short cycle protection for the compressor.
NOTE: The 5 minute anti-short cycle also occurs at
power up.
Random Start
- The control features a random start upon
power up of from 5-80 seconds.
Fault Retry
- In Fault Retry mode, the Status LED
begins slow flashing to signal that the control is trying to
recover from a fault input. The CXM control will stage
off the outputs and then “try again” to satisfy the thermo-
stat "Y" input call. Once the thermostat input calls are
satisfied, the control will continue on as if no fault
occured. If 3 consecutive faults occur without satisfying
the thermostat "Y" input call, then the control will go to
Lockout mode. The last fault causing the lockout will be
stored in memory and can be viewed by going into test
mode.
Lockout
- In Lockout mode, the Status LED will begin
fast flashing. The compressor relay is turned off immedi-
ately. Lockout mode can be soft reset via the thermostat
“Y” input or can be hard reset via the disconnect. The
last fault causing the lockout will be stored in memory
and can be viewed by going into test mode.
Lockout with Emergency Heat
- While in Lockout
mode, if W becomes active, then Emergency Heat mode
will occur.
High Pressure Switch
- When the High Pressure Switch
opens due to high refrigerant pressures, the Compressor
relay is de-energized immediately since the High
Pressure Switch is in series with the compressor
contactor coil. The High Pressure Fault recognition is
immediate as well.
High Pressure Lockout Code = 2
Example: 2 quick flashes, 10 sec pause, 2 quick flashes,
10 sec. pause, etc.
Low Pressure Switch
- The Low Pressure Switch must
be open and remain open for 30 continuous seconds
during "on" cycle to be recognized as a Low Pressure
fault. If the low pressure switch is open for 30 seconds
prior to compressor power up it will be considered a low
pressure (loss of charge) fault. The Low Pressure Switch
input is bypassed for the initial 60 seconds of a compres-
sor run cycle.
Low Pressure Lockout Code = 3
Water Coil Freeze Protection (FP1)
- The FP1 ther-
mistor temperature must be below the selected freeze
protection limit setting for 30 continuous seconds during
a compressor run cycle to be recognized as a FP1 fault.
The FP1 input is bypassed for the initial 60 seconds of a
compressor run cycle.
FP1 Lockout Code = 4
Air Coil Freeze Protection (FP2)
- The FP2 thermistor
temperature must be below the selected freeze protection
limit setting for 30 continuous seconds during a compres-
sor run cycle to be recognized as a FP2 fault. The FP2
input is bypassed for the initial 60 seconds of a compres-
sor run cycle.
FP2 Lockout Code = 5
Condensate Overflow
- The Condensate Overflow sensor
must sense overflow levels for 30 continuous seconds to
be recognized as a CO fault. Condensate Overflow will
be monitored at all times.
CO Lockout Code = 6
Over/Under Voltage Shutdown
- An Over/Under
Voltage condition exists when the control voltage is
outside the range of 19Vac to 30Vac. Over/Under
Voltage Shutdown is self resetting in that if the voltage
comes back within range of 19Vac to 30Vac for at least
0.5 seconds, then normal operation is restored. This is
not considered a fault or lockout. If the CXM is in over/
under voltage shutdown for 15 minutes, the alarm relay
will close.
Over/Under Voltage Shutdown Code = 7
Unit Performance Sentinel-UPS
(patent pending) - The
UPS feature warns when the heat pump is operating
inefficiently. A UPS condition (code 8) exists when:
a) in heating mode with compressor energized, if FP2 is
greater than 125
°
F for 30 continuous seconds, or
b) in cooling mode with compressor energized, if FP1 is
greater than 125
°
F for 30 continuous seconds, OR FP2 is
less than 40
°
F for 30 continuous seconds.
If a UPS condition occurs, the control will immediately
go to UPS warning. The status LED will remain on as if
the control is on Normal mode. (see"LED and Alarm
Relay Operation Table" ). Outputs of the control,
Safety Features
