Application, Operation, & Maintenance Manual | DXM2 UNIT CONTROLS | Heat Controller, Inc. |
Basic Troubleshooting Information
General Troubleshooting
Basic DXM2 board troubleshooting in general is best summarized as simply verifying inputs and outputs. After this process has been verified, confidence in board operation is confirmed and the trouble must be else where. Below are some general guidelines required for developing training materials and procedures when applying the DXM2 Control.
DXM2 Field Inputs
All conventional inputs are 24VAC from the thermostat and can be verified using a voltmeter between C and Y1, Y2, W, O, and G.
Sensor Inputs
All sensor inputs are ‘paired wires’ connecting each component with the board. Therefore continuity on pressure switches can be checked at the board connector.
The thermistor resistance should be measured with the connector removed so that only the impedance of the thermistor is measured. If desired, this reading can be compared to the chart shown in the thermistor section of this manual based upon the actual temperature of the thermistor clip. An ice bath can be used to check calibration of a thermistor if needed.
DXM2 Outputs
The compressor relay is 24VAC and can be verified using a voltmeter. The Alarm Relay can either be 24VAC as shipped or dry contacts (measure continuity during fault) for use with DDC by clipping the J4 jumper. Electric heat outputs are 24VDC and require a voltmeter set for DC to verify operation. When troubleshooting, measure from 24VDC terminal to EH1 or EH2 terminals.
Test Mode
Test Mode can be entered for 20 minutes by pressing the Test button. For Diagnostic ease at a conventional thermostat, the Alarm Relay will also cycle during test mode. The Alarm Relay will cycle on and off similar to the Fault LED to indicate a code representing the last fault, at the thermostat. Test Mode can also be entered and exited by cycling the G input, 3 times within a 60 second time period.
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