Coleman Furnace Rapid Green Flash (CP9C Echelon Modulating)
WarningShown as: Green LED flashing rapidly
The control is in Factory Speed-up mode, used only during factory run-testing. Cycling power to the furnace off and back on stops it.
Manual wording: “Rapid Green Flash - Control is in "Factory Speed-up" mode. This mode is used only during factory run-testing of the furnace. To stop this mode, cycle power to the furnace off and then back on.”
Documented for: CP9C Echelon modulating furnaces
Likely causes, most common first
- Control left in factory run-test (speed-up) mode
What you can safely check yourself
- Turn the furnace off at the service switch for a minute, then back on once
When to call a technician
If a power cycle does not clear it, have a technician check the control board.
A Coleman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Manual - Residential Gas Furnace with ECM Motor, Models TP9C*C, YP9C*C, CP9C*C, LP9C*C (Up to 98% Modulating Multi-position), 681292-UIM-B-1211 (Johnson Controls Unitary Products (Coleman), CP9C*C Coleman Echelon modulating gas furnace (manual also covers the identical TP9C, YP9C and LP9C chassis)) · checked 2026-08-25