Tech Team · Kintek Solution

A furnace's pressure switch is a critical safety device that ensures proper airflow and combustion. When it keeps tripping, it indicates an issue with the furnace's operation, which could stem from a blocked vent, a malfunctioning inducer motor, or a faulty pressure switch itself. Diagnosing the problem requires a systematic approach to identify and address the root cause, ensuring the furnace operates safely and efficiently.

Key Points Explained:

1. Understanding the Pressure Switch Function:

   • The pressure switch monitors the airflow in the furnace. It ensures that the inducer motor is creating enough suction to vent combustion gases safely outside.
   • If the pressure switch detects insufficient airflow, it trips to prevent unsafe operation, such as the buildup of carbon monoxide.

2. Common Causes of Pressure Switch Tripping:

   • Blocked Vent or Flue: A blocked vent or flue can restrict airflow, causing the pressure switch to trip. This blockage could be due to debris, ice, or animal nests.
   • Faulty Inducer Motor: The inducer motor creates the necessary suction. If it fails or operates weakly, the pressure switch may not engage properly.
   • Cracked or Leaking Hose: The pressure switch is connected to the furnace via a hose. If this hose is cracked or leaking, it can cause inaccurate pressure readings.
   • Dirty or Faulty Pressure Switch: Over time, the pressure switch can become dirty or fail mechanically, leading to incorrect operation.

3. Diagnostic Steps:

   • Inspect the Vent and Flue: Check for blockages or obstructions. Clear any debris or ice buildup to restore proper airflow.
   • Test the Inducer Motor: Ensure the inducer motor is functioning correctly. Listen for unusual noises or check if it starts and runs smoothly.
   • Examine the Pressure Switch Hose: Inspect the hose for cracks, leaks, or disconnections. Replace it if necessary.
   • Clean or Replace the Pressure Switch: If the switch is dirty, clean it carefully. If it's faulty, replace it with a compatible model.

4. Preventive Measures:

   • Regularly inspect and clean the vent and flue to prevent blockages.
   • Schedule annual maintenance for the furnace to ensure all components, including the inducer motor and pressure switch, are in good working condition.
   • Replace worn-out hoses or components proactively to avoid unexpected failures.

5. When to Call a Professional:

   • If the issue persists after performing basic troubleshooting, it’s advisable to contact a certified HVAC technician. They can perform advanced diagnostics and ensure the furnace is repaired safely and effectively.

By addressing these key points, you can identify and resolve the issue causing the pressure switch to trip, ensuring your furnace operates safely and efficiently. Regular maintenance and prompt attention to issues can prevent recurring problems and extend the lifespan of your furnace.

Summary Table:

Issue	Cause	Solution
Blocked Vent or Flue	Debris, ice, or animal nests restrict airflow.	Inspect and clear blockages from the vent or flue.
Faulty Inducer Motor	Motor fails or operates weakly, reducing suction.	Test the motor; replace if necessary.
Cracked or Leaking Hose	Hose connected to the pressure switch is damaged or leaking.	Inspect the hose; replace if cracked or leaking.
Dirty or Faulty Pressure Switch	Switch is dirty or mechanically failed.	Clean the switch or replace it with a compatible model.

Still having issues with your furnace pressure switch? Contact our HVAC experts today for professional help!