HVAC Code Lookup

York Furnace 4 Amber Flashes

WarningShown as: Four amber flashes, then a two-second pause, repeating

The control is receiving a Y (cooling) signal from the thermostat without a G (fan) signal. The furnace still heats and cools normally, but the wiring is wrong and the code is displayed to flag it.

Manual wording: “4 AMBER FLASHES: The control is receiving a "Y" signal from the thermostat without a "G" signal... Verify that the "G" wire from the thermostat is connected properly.”

Documented for: TG8S, TG9S, TM9E, TM9X, TM8X, TM9T, TM8T, TM9V, TM8Y, TM9Y

Likely causes, most common first

  1. The G wire from the thermostat is not connected properly

What you can safely check yourself

  • If a new thermostat was recently installed, mention it to the technician - the G (fan) wire is most likely off or on the wrong terminal

When to call a technician

Thermostat wiring corrections are quick for a technician. Left alone, the indoor blower may not run correctly during cooling.

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

Sources

Other York codes