York YP9C two red flashes: the draft proving circuit did not behave

What Does Error 2 red flashes Mean?

Two red flashes on a York YP9C control points at the draft proving circuit: the pressure switch has not reached the state the control expects for the stage of the sequence it is in. The count identifies the circuit, not the component, so the inducer, the vent path, the condensate arrangement, and the switch itself are all inside the reading. Applies to: York YP9C modulating condensing gas furnaces documented in the York installation manual This applies to the York YP9C modulating condensing furnace as documented in its installation manual. York uses different flash tables on other furnace lines, and a modulating furnace proves draft across more than one firing rate, which changes what a fault at a particular stage implies compared with a single-stage appliance. Owner-safe checks: Count the flashes carefully through the sight glass, keeping the blower door closed so control power is not interrupted. | Check the outdoor vent and intake terminations from ground level for snow, ice, nests, or plant growth without climbing or probing. | Note whether ignition is ever attempted and whether the fault is linked to a change in firing rate. Qualified technician: Measuring draft pressure, testing the inducer, clearing condensate traps, and verifying switch operation at each firing rate are licensed gas-furnace tasks. | Any indoor smell of combustion products, or a carbon monoxide alarm, means leaving the appliance off, getting fresh air into the space, and calling the gas emergency number before anything else.

Other Common York furnace — York YP9C modulating condensing gas furnaces documented in the York installation manual Error Codes