P3UR - Flashing Code 2

York Gas Furnace: P3UR / P3DH

Re: Flashing Code 2

Code 2 = Pressure switch stuck closed

The furnace pressure switch should only close when the inducer fan output is energized. If control board is not energizing the inducer fan output and the pressure switch circuit is closed, the board will flash a Code 2.

► A Code 2 will usually keep the inducer motor from starting (unless the relay is stuck) and the gas furnace from operating.

Qty	Possible Causes:
1	Bad Pressure Switch
	Inducer Fan Stuck On (Bad Control Board)
	ADPS Switch Set Too Low

CHECKOUT:

1. Check Controller

Check for 24VAC power from "W" to "C".
- Inducer fan should not be operating with no power on "W".
  - No Power on "W" + Inducer Running = Bad Control Board
    - Inducer may continue to run for "post-purge" after a call for heat for up to 30 seconds.
    - Inducer may also run if a limit is tripped.

2. Check Pressure Switch Contacts

DO NOT PULL THE WIRES OFF OF THE SWITCH - MAY RESET STUCK CONTACTS!
Check for 24VAC from both sides of the switch to "C".
- Power on One Side Only = Switch Open
- Power on Both Sides = Switch Closed
  - Switch Closed + Inducer Off = Bad Pressure Switch

3. ADPS Switch Setting

The ADPS switch will sometimes fail to re-open when set for the lowest setting.