DNH - Indoor Blower Not Operating

York Package Unit: DNH

Re: Indoor Blower Not Operating

CHECKOUT:

1. Check Line Voltage

• Check for 230VAC at the compressor contactor inlet.
  • No Power ⇒ Check Disconnect Switch & Breaker.
    • Before resetting a tripped breaker, check the outlet side of the compressor contactor for a short-to-ground.

2. Check Low Voltage

• At the thermostat, set the Fan Switch to the "On" position.
• At the unit, check for 24VAC at the LTB between "R" and "C".
  • No Power = Blown Low Voltage Fuse, Open Limit Circuit or Bad Transformer
• Check for 24VAC at the LTB between "G" and "C".
  • Power + No Fan Operation → Step 3. Check Control Board
  • ​​​​​​​No Power = Bad Control Wire or Bad Thermostat ⇒ At the thermostat, place a jumper wire from "R" to "G", then re-check power on "G" at the unit.
    • ​​​​​​​Power = Bad Thermostat
    • No Power = Bad Control Wire

3. Check Control Board

• Check for 230VAC at the control board between S1 and Neutral.
  • ​​​​​​​No Power = Bad Wiring
• ​​​​​​​Check for 230VAC at the control board between "Heat" and "Neutral", then "Cool" and "Neutral".
  • ​​​​​​​No Power = Bad Control Board
  • Power + No Blower Operation → Step 4. Check Blower Wheel, Motor & Capacitor

​​​​​​​4. Check Blower Wheel, Motor & Capacitor

► The 2 - 4 Ton Models use a standard, PSC Motor. The 5 Ton Model uses a Variable-Speed, ECM Motor

• Disconnect high voltage power to the unit.
• Manually turn the blower wheel to check wheel & motor bearings.
  • Wheel Loose or Wobbly on Shaft = Broken Blower Wheel
  • Motor Stiff or Won't Turn = Bad Blower Motor
• 2 - 4 Ton Models
• Check the blower motor capacitor.
  • Capacity Less than 80% of Rating = Bad Capacitor
• 5 Ton Models
• Re-Apply power to the unit.
• Energize a call for "Fan-Only".
• Check for 24VAC between "C" and the "Cool" terminal on the control board.
• Check for 24VAC between "C" and the "Heat" terminal on the control board.
  • 24V Power on "Heat" or "Cool" + No Blower Operation = Bad Blower Motor
  • No Power on "Heat" or "Cool" = No Call for "G" or Bad Control Board.​​​​​​​