Heat Controller DXM2 Controls, DXM2 UNIT CONTROLS, Heat Controller, Inc, Diagnostic Features

Heat Controller, Inc. DXM2 UNIT CONTROLS Application, Operation, & Maintenance Manual

DXM2 Controls

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 Overflow - The Condensate Overflow sensor must sense overflow levels for 30 continuous seconds to be recognized as a CO fault. Condensate Overflow 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 Overflow 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 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 (Whole House Dehumidification 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 Dehumidification 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 flash 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.

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