York Package Unit: DNQ

Re: Variable Speed Blower Not Running - Cooling

The unit is calling for either Fan or Cooling, but the indoor blower is not operating.

CHECKOUT:

1. Check Operation

• Make sure the thermostat is set correctly and calling for Fan or Cooling.
• Check to see if sufficient air flow is coming from the supply registers.
  • No Airflow → Step 2. Check Line Voltage Power

2. Check Line Voltage Power

• At the outdoor unit, remove the control access panel.
• Look for any signs of burnt wires or controls.
• Check for 230V power across each power supply (at the compressor contactor).
  • Power Present → Step 3. Check Low Voltage Power
  • No Power = Check the Service Disconnect and Breaker
    • If the breaker is tripped, check the compressor windings for a short-to-ground before resetting the breaker.

3. Check Low Voltage Power

• Check for 24VAC between "R" and "C" on the low voltage wiring.
  • No Power = Blown Low Voltage Fuse or Bad Transformer ⇒ Check the low voltage fuse first (if present).  If the fuse is good, check the low voltage output of the transformer.
• Check for 24VAC between "G" and "C" on the low voltage wiring.
  • No Power = No Call for Fan
  • Power Present + No Blower Operation → Step 4. Check Blower Motor
• Check for 24VAC between "Y" and "C" on the low voltage wiring.
  • No Power = No call for Cooling
  • Power Present + No Blower Operation →  Step 4. Check Blower Motor

4. Check Blower Motor

• Check Blower Motor
  • At the Motor High Voltage Plug, check for 230V across "Prp" at Pin#4 and "Blk" at Pin#5 on the ECM motor.
    • No Power = Burnt or Bad Wiring
  • At the 16-pin motor connection, check for 24VAC between "R/R" at Pin#12 and "C1/Br" at Pin#1.
    • No Power = Bad Wiring Harness or Bad ECM Board
  • At the 16-pin motor connection, check for 24VAC between "G/PR" at Pin#15 and "C1/Br" at Pin#1.
    • No Power = Bad Wiring Harness or Bad ECM Board
    • Power + No Blower Operation = Bad Motor/Controller