Carrier furnace status code 31: pressure switch did not close

What Does Error 31 Mean?

Carrier assigns status code 31 to a high-heat pressure switch input that did not close when the control called for high or intermediate heat, or that opened during the heat cycle. It reports the state of a proving circuit, so the draft inducer, venting, condensate, tubing, wiring, and the switch itself all stay on the list until one is confirmed. Applies to: Carrier two-stage and variable-speed modulating condensing furnaces that report status code 31 This reading follows Carrier service literature for two-stage and modulating condensing furnaces that flash a two-digit status code. Single-stage models and other code numbers behave differently, and the legend printed inside the furnace door is what confirms the meaning for a given board. Owner-safe checks: With the furnace off, clear any frost, ice, snow, or debris from the outdoor vent and intake terminations and confirm the terminations are not obstructed. | Check the furnace filter is clean, the return and supply grilles are open, and the furnace access door is fully closed. Qualified technician: Measuring inducer pressure, testing the switch and inducer, clearing the condensate trap, and any wiring or gas-valve work require a qualified heating technician, and the pressure switch must never be bypassed.