York Furnace 1 Amber Flash (YP9C Modulating)
StatusShown as: One amber flash, two-second pause, repeating
Normal operation with a call for cooling. Not a fault.
Manual wording: “One Amber Flash - Normal operation with call for cooling.”
Documented for: YP9C, YPLC modulating furnaces
Likely causes, most common first
- Normal air conditioning operation
When to call a technician
No service needed.
A York furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Manual - Modulating ECM Residential Gas Furnace with ECM Motor, Models YP9C*C / TP9C*C / CP9C*C / LP9C*C (Up to 98% Modulating Multi-position), 1083292-UIM-A-0114 (Johnson Controls Unitary Products (York), YP9C*C (York Affinity modulating), and the identical TP9C / CP9C / LP9C chassis) · checked 2026-08-25