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.