Furnace Pressure Switch Problems: Open, Closed and Draft Conditions

A furnace pressure-switch message describes a model-specific operating condition in the draft-proving circuit. The cause can involve the switch, sensing circuit, inducer, venting or drainage. Keep the controls intact and record the exact message. Diagnosis should distinguish a failed switch from a switch responding to another problem.

A Pressure Switch Is Part of the Draft-Proving System

On gas furnaces that use one, a pressure switch provides operating information related to the combustion-air or venting sequence. The control expects a particular circuit state at a particular point. The arrangement, number of switches and required values depend on the model.

An open-switch message can therefore describe a condition that has not been met. A closed-switch message can describe an unexpected circuit state at another stage. Neither wording proves the switch itself has failed. The technician must establish what the furnace expects and why the actual condition differs.

Why Venting, Drainage and the Inducer May Be Relevant

The switch is connected to an operating system. A restriction, a drainage issue on applicable equipment, an inducer concern or a sensing-circuit problem may affect what it reports. The correct test compares the actual conditions with the installed model’s requirements instead of using a universal setting.

You can describe an accessible exterior termination from ground level without touching it. Report obvious damage, obstruction or water near the furnace. Do not climb, disconnect piping, put objects into a vent or alter its termination. The water near the furnace guide explains why drainage and a shutdown can be related.

Do Not Bypass, Adjust or Force the Switch

Bridging a switch to make the furnace fire removes an operating protection and does not correct the condition. Leave the switch, its tubing and the wiring intact. Blowing into a sensing hose, applying suction or changing an adjustment is not a homeowner diagnostic method.

A code disappearing after manipulation would not establish that the venting or combustion conditions are acceptable. Ask the technician to explain the cause and the checks needed before returning the furnace to use. If there is gas odour or a CO alarm, follow the emergency instructions rather than investigating the switch.

Replacement Parts Need the Correct Application

Pressure switches can differ in setpoint, staging, connections and approved use. A similar housing does not establish compatibility. Use the complete furnace model and manufacturer parts information, including an approved supersession if the original reference has changed.

The Goodman manufacturer parts finder, for example, lists different pressure-switch references for different complete furnace models. That is an illustration of model-specific identification, not a recommendation to fit a Goodman part to another furnace. Our parts overview explains the information needed before a purchase.

Prepare a Useful Fault Description

Record the exact code, whether a small motor begins running before the failure and whether ignition ever occurs. Mention water, unusual noises, recent venting work and previous switch replacement. Use an external viewing window or existing records; do not open a cabinet to obtain a picture.

For the repair discussion, ask whether the switch failed its applicable checks or responded to another condition. Confirm the repair scope, compatible part where needed and operating checks afterward. Use furnace repair for an active shutdown and the code-recording guide to preserve the information. Avoid repeated resets while waiting for advice.

Keep the original fault description and any repair findings together. If the message returns after another visit, explain whether the operating pattern is the same and which part or drainage work was completed. That history helps guide a fresh assessment.

Published by SkyLimit Heating & Gas. Updated November 7, 2026. General homeowner information; internal gas, electrical and combustion work requires qualified assessment.