Carrier Gas Furnaces: 58MXA

Re: Flashing Code 23 / Fault Code 23

Diagnostic Light Sequence: 2-Short Flashes, 3-Long Flashes (- - , — — —)

Code 23 indicates that the furnace pressure switch is closed when it should be open.

CHECKOUT:

1. Check Furnace Operation

• Start the furnace with NO call for heat.
• Ensure that the inducer motor stops.
  • Inducer Motor Continues to Run = Bad Control Board or Mis-Wired Inducer