Heat Controller DXM2 Application And Instruction Manual page 9

Heat Controller, Inc.
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
UPS feature warns when the heat pump is operating
ineffi ciently. 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.
DXM2 UNIT CONTROLS
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.
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 (Whole
House Dehumidifi cation 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 (Whole House
Dehumidifi cation 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.
Diagnostic Features
The green Status LED and red Fault LED on the DXM2
Control advise service personnel of the current status of
the DXM2 Control. The LED's will indicate the current
operating status of the DXM2, as well as the LAST fault in
memory. If there is no fault in memory and the fault display
is selected, the Fault LED will fl ash Code 1. See Table 3 for
a complete listing of codes.
UNIT OPERATION DESCRIPTION
Power Up - The unit will not operate until all the inputs and
safety controls are checked for normal conditions.
9
Application, Operation, & Maintenance Manual
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
confi guration is incorrect or incomplete. For this
fault condition, the control will continue to operate
using default operating parameters.
DXM2 Controls