51
Troubleshooting Guide -
Tranquility
®
Digital (DXM2) Packaged Units
Rev.: 01/15/14
CAUTION!
CAUTION!
Do not restart units without inspection and rem-
edy of faulting condition. Equipment damage may occur.
DXM2 Controls
start upon power up. The random start delay will be present
after a control power up and after returning from Night
Setback or Emergency Shutdown modes.
Extended Compressor Operation Monitoring - If the
compressor relay has been on for 4 continuous hours, then
the control will automatically turn off the compressor relay
and wait the short cycle protection time. All appropriate
safeties will be monitored during the off time. If all operation
is normal, and if the compressor demand is still present, the
control will turn the compressor back on.
Fault Retry - In Fault Retry Mode, the Fault LED begins slow
fl ashing to signal that the control is trying to recover from a
fault input. The DXM2 Control will stage off the outputs and
then “try again” to satisfy the thermostat call for compressor.
Once the thermostat input calls are satisfi ed, the control will
continue on as if no fault occurred. If 3 consecutive faults
occur without satisfying the thermostat call for compressor,
then the control will go to Lockout Mode. The last fault
causing the lockout will be stored in memory and is displayed
at the Fault LED by entering the Test mode.
Note: LT1 and LT2 faults are factory set for one try, so
there will be no “retries” for LT1 and LT2 faults. The
control will only try one time for these faults.
FAULT CODES
Lockout - In Lockout Mode, the Fault LED will begin fast
fl ashing. The compressor relay is turned off immediately.
The fan output will be turned off after the current blower off
delay unless auxiliary heat is active. The Lockout Mode can
be “soft” reset via the thermostat by removing the call for
compressor, or by a “hard” reset (disconnecting power to the
control). The fault code will be stored in non-volatile memory
that can be displayed by the Fault LED by entering the Test
mode, even if power was removed from the control.
Lockout with Emergency Heat - If the DXM2 is confi g-
ured for Heat Pump thermostat Mode (see DIP 1.3), the
DXM2 is in Lockout Mode, and the W input becomes active,
then Emergency Heat Mode will occur during Lockout. For
Emergency Heat, the fan and auxiliary heat outputs will be
activated.
Fault Code 2: High Pressure Switch – When the High
Pressure switch opens due to high refrigerant pressures, the
compressor relay is de–energized immediately. The High
Pressure fault recognition is immediate (does not delay for 30
continuous seconds before de–energizing the compressor).
When the Test mode is activated, the Fault LED will display a
fault code of 2 for a High Pressure fault.
Fault Code 3: Loss of Charge Switch – The Loss of Charge
Switch must be open and remain open for 30 continuous
seconds during a compressor “on” cycle to be recognized
as a Loss of Charge fault. If the Loss of Charge switch is
open for 30 seconds prior to compressor power up it will
be considered a Loss of Charge fault. The Loss of Charge
Switch input is bypassed for the initial 120 seconds of a
compressor run cycle. When the Test mode is active, the
Fault LED will display a fault code of 3 for a Loss of Charge
fault.
Fault Code 4: Water Coil Low Temperature Cut-Out Limit
(LT1) - The control will recognize an LT1 fault, during a
compressor run cycle if:
a) the LT1 thermistor temperature is below the selected
low temperature protection limit setting for at least 50
seconds, AND
b) the LT1 thermistor temperature is rising (getting
warmer) at a rate LESS than 2°F per 30 second time
period.
The LT1 input is bypassed for the initial 120 seconds of a
compressor run cycle. When the Test mode is active, the
Fault LED will display a fault code of 4 for a LT1 fault.
Fault Code 5: Air Coil Low Temperature Cut-Out (LT2) -
The control will recognize an LT2 fault, during a compressor
run cycle if:
a) the LT2 thermistor temperature is below the low
temperature protection limit setting for at least 50
seconds, AND
b) the LT2 thermistor temperature is rising (getting
warmer) at a rate LESS than 2°F per 30 second time
period.
The LT2 input is bypassed for the initial 120 seconds of a
compressor run cycle. When the Test mode is active, the
Fault LED will display a fault code of 5 for a LT2 fault.
Fault Code 6: Condensate Overfl ow - The Condensate
Overfl ow sensor must sense overfl ow levels for 30
continuous seconds to be recognized as a CO fault.
Condensate Overfl ow will be monitored at all times during
the compressor run cycle. When the Test mode is active,
the Fault LED will display a fault code of 6 for a Condensate
Overfl ow fault.
Fault Code 7: Over/Under Voltage Shutdown - An Over/
Under Voltage condition exists when the control voltage is
outside the range of 18VAC to 31.5VAC. Over/UnderVoltage
Shutdown is self-resetting in that if the voltage comes back
within range of 18.5VAC to 31VAC for at least 0.5 seconds,
then normal operation is restored. This is not considered
a fault or lockout. If the DXM2 is in over/under voltage
shutdown for 15 minutes, the Alarm Relay will close. When
the Test mode is active, the Fault LED will display a fault
code of 7 for an Over/Under Voltage Shutdown.
Fault Code 8: Unit Performance Sentinel – UPS – The
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