CXM Control
For detailed control information, see CXM Electronic Heat
Pump Control Application, Operation and Maintenance
Guide.
Field Selectable Inputs
Test mode: Test mode allows the service technician to
check the operation of the control in a timely manner. By
momentarily shorting the test terminals, the CXM control
enters a 0 minute test mode period in which all time
delays are sped up 15 times. Upon entering test mode,
the status LED will flash a code representing the last fault.
For diagnostic ease at the thermostat, the alarm relay will
also cycle during test mode. The alarm relay will cycle
on and off similar to the status LED to indicate a code
representing the last fault, at the thermostat. Test mode
can be exited by shorting the test terminals for seconds.
Retry Mode: If the control is attempting a retry of a fault,
the status LED will slow flash (slow flash = one flash
every seconds) to indicate the control is in the process
of retrying.
Field Configuration Options
Note: In the following field configuration options, jumper
wires should be clipped ONLY when power is removed
from the CXM control.
Air coil low temperature limit setting: Jumper (JW-FP
Low Temp) provides field selection of temperature limit
setting for FP of 0°F or 10°F [-1°F or -1°C] (refrigerant
temperature). Note: This jumper should only be clipped
under extenuating circumstances, as recommended by
Heat Controller technical services.
Not Clipped = 0°F [-1°C]. Clipped = 10°F [-1°C].
Alarm relay setting: Jumper 1 (JW1-AL Dry) provides
field selection of the alarm relay terminal AL to be
jumpered to 4VAC or to be a dry contact (no connection).
Not Clipped = AL connected to R. Clipped = AL dry
contact (no connection).
DIP Switches
Note: In the following field configuration options, DIP
switches should only be changed when power is removed
from the CXM control.
DIP switch 1: Unit Performance Sentinel Disable -
provides field selection to disable the UPS feature.
On = Enabled. Off = Disabled.
DIP switch :
On = Always
DIP switch : Not Used.
DIP switch 4: DDC Output at EH - provides selection for
DDC operation. If set to “DDC Output at EH,” the EH
terminal will continuously output the last fault code of
the controller. If set to “EH normal,” EH will operate as
standard electric heat output.
On = EH Normal. Off = DDC Output at EH.
DIP switch 5: Factory Setting - Normal position is “On.”
Do not change selection unless instructed to do so by
the factory.
Description of Operation
LED
Alarm Relay
Normal Mode
On
Open
Normal Mode with UPS Warning
On
Cycle (closed 5 sec., Open 5 sec.)
CXM is non-functional
Off
Open
Fault Retry
Slow Flash
Open
Lockout
Fast Flash
Closed
Over/Under Voltage Shutdown
Slow Flash
Open (Closed after 15 minutes)
Test Mode - No fault in memory
Flashing Code 1
Cycling Code 1
Test Mode - HP Fault in memory Flashing Code
Cycling Code
Test Mode - LP Fault in memory
Flashing Code
Cycling Code
Test Mode - FP1 Fault in memory Flashing Code 4
Cycling Code 4
Test Mode - FP Fault in memory Flashing Code 5
Cycling Code 5
Test Mode - CO Fault in memory Flashing Code 6
Cycling Code 6
Test Mode - Over/Under
shutdown in memory
Flashing Code 7
Cycling Code 7
Test Mode - UPS in memory
Flashing Code 8
Cycling Code 8
Test Mode - Swapped Thermistor Flashing Code
Cycling Code
CXM CONTROLS
Table 6: CXM LED And Alarm
Relay Operations
CONTROLS - SAFETY FEATURES
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
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 by going into test mode on the CXM
board. Note: FP1/FP 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, emergency heat mode will occur.
-Slow Flash = 1 flash every seconds
-Fast Flash = flashes every 1 second
-Flash code = quick flashes, 10 second pause, quick
flashes, 10 second pause, etc.
-On pulse 1/ second; off pulse 1/ second
