HVAC Code Lookup

York Furnace 5 Amber Flashes (YP9C Modulating)

WarningShown as: Five amber flashes, two-second pause, repeating

The furnace has cut back its heating output because the combustion air or vent system is restricted. Above 4,000 feet altitude this can also be normal automatic derating.

Manual wording: “Five Amber Flashes - Heating capacity is reduced due to restriction in the combustion air or vent system. Check for blocked vent/air pipe or clogged condensate drain.”

Documented for: YP9C, YPLC modulating furnaces

Likely causes, most common first

  1. Blocked vent or air intake pipe
  2. Clogged condensate drain
  3. Normal altitude derating above 4,000 feet

What you can safely check yourself

  • Check the outside vent and intake pipe terminations for snow, ice, leaves or nests
  • Check the condensate drain and trap for a clog

When to call a technician

If the pipes and drain are clear and you are not at high altitude, have a technician check the venting and inducer.

A York furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Source

Other York codes