York Package Unit: DNQ
Re: Variable Speed Blower Not Running - Heating
The unit is calling for either Heating, but the indoor blower is not operating.
Qty |
Possible Causes: |
4 |
Bad Blower Motor/Controller |
|
Bad ECM Control Board |
|
Tripped Breaker |
|
Bad/Burnt Wiring |
CHECKOUT:
1. Check Operation
- Make sure the thermostat is set correctly and calling for Heating.
- Check to see if sufficient air flow is coming from the supply registers.
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 "W1" and "C" on the low voltage wiring.
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 Plug, 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 "W/WHT" at Pin#2 and "C1/Br" at Pin#1.
- Power + No Blower Operation = Bad Motor/Controller
- No Power = Bad Wiring Harness or Bad Ignition Board
- The "W/WHT" wire connects to the Ignition Control Board, 24V "HEAT" fan terminal.