Payne PG8MAA Error Code Pressure Switch Did Not Close or Reopened: Pressure Switch Did Not Close or Reopened

What Does Code Pressure Switch Did Not Close or Reopened Mean?

Status code 31 on the Payne PG8MAA means the pressure switch failed to close when the inducer motor started, or it reopened during furnace operation. The pressure switch is a safety device that confirms the inducer motor is generating enough draft to safely vent combustion gases before the gas valve opens.

When the inducer starts, it creates negative pressure inside the heat exchanger and vent system. The pressure switch senses this draft and closes, telling the control board it is safe to proceed with ignition. If something is blocking airflow — a clogged vent, plugged condensate drain, or disconnected pressure tubing — the inducer cannot build enough draft to satisfy the switch.

If the pressure switch remains open for longer than 5 minutes, the inducer shuts off for 15 minutes before retrying. If the switch opens during the blower on-delay period, the blower will run for the selected blower off-delay time. Common seasonal causes include ice or snow blocking the outdoor vent termination in winter, and bird nests or insect nests in warmer months.

Common Causes

How to Fix It: Check Exhaust Vent, Condensate Drain, and Pressure Tubing

What You'll Need

• Flashlight
• Mirror (optional, for checking inside vent pipe)

Steps

1. Turn off power at the breaker or power switch and shut off the gas supply valve Locate your electrical panel and turn the furnace breaker to OFF. Find the gas shutoff valve on the gas line leading to the furnace and turn it to the closed (perpendicular to the pipe) position. If you smell gas, leave immediately and call your gas company.
2. Inspect the exhaust vent termination outside Go outside and locate where the furnace exhaust vent exits your home (typically a PVC pipe through the side wall or roof). Check for any visible blockage: snow, ice, bird nests, leaves, insect nests, or debris. Clear any obstructions you find. In winter, ice buildup around the vent termination is one of the most common causes of this code.
3. Check the condensate drain Locate the condensate drain line — it typically runs from the inducer housing or a collector box to a floor drain or condensate pump. Check that the drain line is not kinked, clogged, or frozen. If water is pooled around the inducer area, the drain is likely blocked. Clear any visible blockage.
4. Visually check the pressure tubing Look at the small rubber or vinyl tube(s) running from the pressure switch to the inducer housing. Make sure they are connected at both ends, not kinked, cracked, or visibly clogged. If a tube has disconnected, push it firmly back onto the barb fitting.
5. Restore power and gas Turn the gas supply valve back to open (parallel to the pipe). Turn the breaker back ON. Set the thermostat to call for heat and observe whether the furnace proceeds past the inducer startup stage.

When to Call a Professional

Contact a licensed HVAC technician if:

• The exhaust vent and condensate drain appear clear but code 31 persists
• The inducer motor sounds unusually loud, weak, or does not run at all
• Water consistently pools in the inducer housing despite clearing the drain
• Code 31 appears mainly during windy weather (may need a vent wind guard)
• The pressure tubing appears intact but the switch still does not close
• The inducer shuts off after 5 minutes and retries repeatedly without success