York furnace error codes

Flame was sensed when there was not a call for heat. The control turns on both the inducer motor and the supply air blower.

The main limit switch has opened and stayed open for more than five minutes. The manual says this is usually a failed blower motor or blower wheel. The control is in a hard lockout. Power has to be cycled off and on only after the problem is corrected.

The gas valve is energized with no call for heat. The main blower and the inducer blower run, and no ignition sequence starts, for as long as this condition exists.

The pressure switch is closed when it should be open. The control checks that the contacts are open at the start of each heat cycle and will not continue ignition if they are already closed.

The main limit switch has opened its normally closed contacts. The control runs the supply air blower and the inducer while the limit stays open.

The pressure switch contacts are open when they should be closed.

The flame could not be established during three trials for ignition. The furnace locks out for one hour and then restarts.

While the furnace was operating, the pressure switch opened four times during the call for heat. The furnace locks out for one hour and then restarts.

The flame was lost five times (four recycles) during the heating cycle. The furnace locks out for one hour and then restarts.

The normally closed rollout switch has opened. The rollout control is manually reset. The control enters a hard lockout, and power has to be cycled off and on only after the problem is corrected.

Reversed line-voltage polarity, a grounding problem, or reversed low-voltage transformer wires. Heating and cooling are both affected. The furnace will not start the ignition sequence until this is corrected.

Flame sense current is below 1.5 microamps. The manual's ignition-control levels put a normal flame sense current at about 3.7 microamps DC, the low-flame warning at 1.5 microamps, and the control lockout point at 0.1 microamps DC.