Tranquility
®
D i g i t a l ( D X M 2 ) — Tr o u b l e s h o o t i n g G u i d e
R e v. : 1 0 M a r c h , 2 0 1 5
58
G e o t h e r m a l H e a t i n g a n d C o o l i n g
DXM2 Controls
Fault Code 8: Unit Performance Sentinel – UPS
– The
UPS feature warns when the heat pump is operating
inefficiently. A UPS condition exists when:
a) In Heating Mode with compressor energized, if LT2 is
greater than 125°F for 30 continuous seconds, or
b) In Cooling Mode with compressor energized, if LT1
is greater than 125°F for 30 continuous seconds, OR
LT2 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 in Normal Mode. (see “LED and Alarm Relay Operation
Table”). Outputs of the control, excluding Fault LED and
Alarm Relay, will NOT be affected by UPS. The UPS
condition cannot occur during a compressor off cycle. During
UPS warning, the Alarm Relay will cycle on and off. The cycle
rate will be On for 5 seconds, Off for 25 seconds, On for 5
seconds, Off for 25 seconds, etc. When the Test mode is
active, the Fault LED will display a fault code of 8 for an UPS
condition.
Fault Code 9: Swapped LT1/LT2 Thermistors
- During
Test Mode, the control monitors to see if the LT1 and LT2
thermistors are connected and operating properly. If the
control is in Test Mode, the control will lockout, with Code 9,
after 60 seconds if:
a) the compressor is On in Cooling Mode and the LT1
sensor is colder than the LT2 sensor. Or,
b) the compressor is On in Heating Mode and the LT2
sensor is colder than the LT1 sensor.
When the Test mode is active, the Fault LED will display a
fault code of 9 for a Swapped Thermistor fault.
Fault Code 10: ECM Blower Fault
– When operating
an ECM blower, there are two types of ECM Blower fault
conditions that may be detected.
a) An ECM blower fault will be detected and the control
will lockout after 15 seconds of blower operation with
the blower feedback signal reading less than 100
RPM.
b) An ECM blower fault will be detected when the ECM
configuration is incorrect or incomplete. For this fault
condition, the control will continue to operate using
default operating parameters.
When the Test mode is active, the Fault LED will display a
fault code of 10 for an ECM Blower fault.
Fault Code 11: Low Air Coil Pressure Switch
(Dedicated
Dehumidification Mode Units Only) – When the Low Air Coil
Pressure switch opens due to low refrigerant pressure in the
cooling or reheat operating mode, the compressor relay is
de–energized immediately. The Low Air Coil 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 11 for a Low Air Coil Pressure fault. Note: Low Air Coil
Pressure fault will keep the unit from operating in the cooling
or reheat modes, but heating operation will still operate
normally.
Fault Code 12: Low Air Temperature
(Dedicated
Dehumidification Mode Units Only) – The control will
recognize an Low Air Temperature fault, during cooling,
reheat, or constant fan operation if the LAT thermistor
temperature is below 35 degrees for 30 continuous seconds.
When the Test mode is activated, the Fault LED will display
a fault code of 12 for a Low Air Temperature fault. Note: Low
Air Temperature fault will keep the unit from operating in the
cooling, reheat, or constant fan modes, but heating operation
will still operate normally.
Internal Flow Center Faults
– When operating an internal
flow center, the DXM2 monitors the pump feedback signal
and may detect one of several pump faults. The control may
detect locked rotor, low voltage, no flow, or bad pump sen-
sor conditions that will result in an internal flow center fault.
When the Test mode is active, the Fault LED will display a
fault code of 13 for a internal flow center fault.
ESD
– The ESD (Emergency Shut Down) Mode is utilized
when the ERV (Energy Recovery Ventilator) option is applied
to an TRE series rooftop unit to indicate an ERV fault. A
contact closure at the ERV unit will connect common to the
ESD terminal, which will shut down the rooftop/ERV units.
The green Status LED will flash code 3 when the unit is in
ESD Mode. The ESD Mode can also be enabled from an
external common signal to terminal ESD (see “Thermostat
Inputs” section for details).
