DNZ - Flashing Code 2

Package Unit: DNZ

Re: Flashing Code 2

These units have one control board (EMCB) which controls all unit functions.

► Any heating diagnostics will be displayed on the EMCB.

CODE 2 = Pressure switch "Open" with the inducer motor energized.

CHECKOUT:

1. Check Heating Sequence

• Energize a call for heat from the thermostat.
• Ensure that the inducer motor starts.
  • No Inducer + Code 2 → Step 2. Check Control Board
  • Inducer Starts + Code 2 → Step 4. Check Pressure Switch

2. Check Control Board

• Check for 24VAC between "W1" and "C" on the EMCB.
  • No Power on "W1" = No Call for Heat
• 1-Stage Inducer
• Check for 230VAC between Ignition Control Board [IND] terminal (BLK) and Compressor Contactor L2 (PRP).
  • Power Present + No Inducer Operation → Step 3. Check Inducer
  • No Power = Bad Control Board
• 2-Stage Inducer
• Check for 230VAC between Ignition Control Board [IND] terminal (RED) and Compressor Contactor L2 (WHT).
• Check for 230VAC between Ignition Control Board [H-IND] terminal (BLK) and Compressor Contactor L2 (WHT).
  • Power Present + No Inducer Operation → Step 3. Check Inducer
  • No Power = Bad Control Board

3. Check Inducer Motor

• Check the temperature of the inducer motor.
• Use an Amp Probe to check the amperage of the inducer motor.
  • Power + Hot Motor + No Amperage = Off on Overload ⇒ Turn off power to the unit, allow motor to cool, then recheck.
  • Power + Cool Motor + No Amperage = Bad Inducer Motor
  • Power + Amperage + Not Running = Bad Inducer Motor or Item Stuck in Inducer Wheel ⇒ Remove Inducer Assembly & Check Wheel

4. Check Pressure Switch

• Check for 24VAC between "C" of the EMCB and 245/PRP on the pressure switch.
  • Power Present + Code 2 = Bad Control Board
  • No Power = Open Pressure Switch
    • Use a pressure gauge to check the negative pressure from the inducer.
      • Adequate Negative Pressure = Bad Pressure Switch
      • No or Low Negative Pressure ⇒ 
        • Check for a Clogged Pressure Port. 
        • Remove the inducer assembly and check the condition of the blower wheel.