Safety Features - Cxm Controls - Carrier 50YER036 Installation, Operation And Maintenance Instructions

Safety Features – CXM Control
The safety features below are provided to protect
the compressor, heat exchangers, wiring and other
components 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 5-80 seconds.
Fault Retry: In Fault Retry mode, the Status LED begins
slowly flashing to signal that the control is trying to
recover from a fault input. The control will stage off the
outputs and then "try again" to satisfy the thermostat
input call. Once the thermostat input call is satisfied,
the control will continue on as if no fault occurred. If 3
consecutive faults occur without satisfying the thermostat
input call, the control will go into "lockout" mode. The last
fault causing the lockout will be stored in memory and
can be viewed at the "fault" LED (DXM board) or by going
into test mode (CXM board). Note: FP1/FP2 faults are
factory set at only one try.
Lockout: In lockout mode, the status LED will begin fast
flashing. The compressor relay is turned off immediately.
Lockout mode can be "soft" reset by turning off the
thermostat (or satisfying the call). A "soft" reset keeps
the fault in memory but resets the control. A "hard" reset
(disconnecting power to the control) resets the control
and erases fault memory.
Lockout with emergency heat: While in lockout mode,
if W becomes active (CXM), emergency heat mode will
occur. If DXM is configured for heat pump thermostat
type (DIP 1.3), emergency heat will become active if O/
W2 is energized.
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 (does not delay for 30
continuous seconds before de-energizing the compressor).
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 120 seconds of a compressor run cycle.
W a t e r- t o - W a t e r ( 5 0 Y E R ) S e r i e s - P u r o n

Safety Features - CXM Controls

Low pressure lockout code = 3
Water coil low temperature (FP1): The FP1 thermistor
temperature must be below the selected low
temperature 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 120
seconds of a compressor run cycle. FP1 is set at the
factory for one try. Therefore, the control will go into
lockout mode once the FP1 fault has occurred.
FP1 lockout code = 4
Air coil low temperature (FP2): The FP2 thermistor
temperature must be below the selected low
temperature limit setting for 30 continuous seconds
during a compressor run cycle to be recognized as a
FP2 fault. The FP2 input is bypassed for the initial 120
seconds of a compressor run cycle. FP2 is set at the
factory for one try. Therefore, the control will go into
lockout mode once the FP2 fault has occurred.
FP2 lockout code = 5
Condensate overflow: The condensate overflow sensor
must sense overflow level 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 18VAC to 31.5VAC. Over/under voltage shut
down is a self-resetting safety. If the voltage comes
back within range for at least 0.5 seconds, normal
operation is restored. This is not considered a fault
or lockout. If the CXM/DXM is in over/under voltage
shutdown for 15 minutes, the alarm relay will close.
Over/under voltage shut down code = 7
Unit Performance Sentinel-UPS (patent pending):
The UPS feature indicates when the heat pump is
operating inefficiently. A UPS condition exists when:
a) In heating mode with compressor energized, FP2
is greater than 125°F [52°C] for 30 continuous
seconds, or:
b) In cooling mode with compressor energized, FP1
is greater than 125°F [52°C] for 30 continuous
seconds, or:
c) In cooling mode with compressor energized, FP2 is
less than 40°F [4.5°C] 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 in normal mode. Outputs of the
control, excluding LED and alarm relay, will NOT be
affected by UPS. The UPS condition cannot occur
during a compressor off cycle. During UPS warning,
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