York YP9C modulating gas furnace showing 5 red flashes: meaning and exact next steps

Model-specific

What is true of this model and not of its siblings

Two switches in one code

York names two possible causes for five flashes, a rollout switch and a condensate pressure switch. They are different problems: one is about flame, the other about water, so look for evidence of each before you decide which you are dealing with.

What the rollout switch protects

If burner flames roll out of the burner compartment, for example because the heat exchanger is blocked, the rollout switch opens and stops the gas. Resetting it removes the protection while the cause is still there, so York says to call a servicer if it trips again.

The condensate side

A high efficiency furnace makes acidic water that drains through a trap and a line. A kinked line, a clogged trap or a frozen outdoor discharge fills the trap and opens the condensate switch.

What you can safely do

Check for water, straighten a visibly kinked hose and press the rollout reset once. Do not remove panels, and do not pour chemicals into the trap.

Records

Note the date, the weather and whether water was present. A frozen discharge in cold weather is a different repair from a failed switch.

After service

Ask the technician to say which switch tripped and why, so that a repeat is easier to diagnose.

Telling water from flame

Look first at the floor around the furnace and at the drain line. Water on the floor, a gurgling trap or a drain line that is full points to the condensate side. A scorched look at the burner compartment, a smell of hot metal or soot around the burner door points to the rollout side. If you see soot or scorch marks, leave the furnace off and call at once, since York treats a repeated rollout trip as a sign of a possible heat exchanger or venting problem.

What a technician will do

They check the rollout switch with a meter, look at the burners and the heat exchanger, run the furnace and watch the flame, and check the condensate trap and drain for blockage. A trap can be cleaned and refilled, and a drain line can be flushed. They also look at the vent pipe slope, which should drain toward the furnace.

Before the first cold snap

Have the furnace serviced each autumn. A yearly visit catches a dirty burner, a clogged trap and a tired inducer before they stop the furnace in the cold, and the visit costs far less than an emergency call at night.