If your Goodman furnace is blowing cold air, there is a chance that the pressure switch won’t close or that the pressure switch will open during the cycle for heat. A pressure switch problem is commonly misdiagnosed as a failed switch. This post will discuss why the pressure switch stuck open on the Goodman furnace and how to fix it.
What’s a furnace pressure switch?
A pressure switch in a furnace serves as a kind of safety device, detecting negative pressure, incorrect venting air pressure and proper combustion airflow. If improper conditions are detected, the pressure switch will shut down the furnace ignition to prevent unsafe operation.
The furnace pressure switches are normally open and closed during operation. They monitor the airflow (combustion air and flue products) through the heat exchanger via pressure taps located on the induced draft blower and the coil front cover.
These switches guard against insufficient airflow (combustion air and flue products) through the heat exchanger and/or blocked condensate drain conditions.
Common Issues That Cause A Pressure Switch To Stay Open
A pressure switch stuck open in Goodman Furnaces may indicates a problem elsewhere that needs to be addressed. However, the silver lining is that many of these issues are within the realm of DIY solutions.
Let’s explore the typical causes and how to address them.
Open Switch
When the vent system in a furnace is working properly, the induced draft blower will close the pressure switch. But when a pressure switch doesn’t close and no heat is being produced, common problems include:
- Debris buildup in the draft blower housing
- Failed motor
- Cracked heat exchanger
- Blocked condensate drain
- Stuck pressure switch
- Plugged vent pipe
Pressure switch problems can differ between every Goodman furnace models.
Improper Piping Size and Installation
In many cases, a pressure switch problem relates to the installation or length of combustion air and flue piping or condensate piping within the furnace system. If the length of flue piping is too great or the pipe diameter too short, the pressure switch will stuck open.
The pipe diameter size for the combustion air or flue piping may need to be increased from two inches to three inches.
Another common cause of an open pressure switch is condensate buildup inside the furnace from improper condensate piping installation. The condensate buildup inside the furnace is the most common culprit for causing a pressure switch to stuck open.
Too often, a technician will unknowingly construct an installed condensate piping with what we refer to as a double trap. Be sure your flue and combustion air piping, as well as your condensate piping, is correct before attempting to replace a pressure switch.
Defective Switch
Sometimes the pressure switch itself is defective and need to be replaced. A professional HVAC Technician will use a specialized gauge or manometer to find out if the switch is, in fact, defective and causing the problem in your furnace.
While some issues causing a pressure switch to stay open in your Goodman Furnace can be tackled with DIY methods, others demand professional skills and tools. Regular checks and maintenance can prevent many of these problems, but when in doubt, or for more complex issues, calling in a professional is the safest and most effective approach.
How To Test A Furnace Pressure Switch
Testing your Goodman Furnace’s pressure switch is a practical DIY task that can provide insights into its functioning. This task requires an intermediate level of handling furnace components and electrical testing tools.
Steps to test the furnace pressure switch:
- Turn Off the Power
- Safety is paramount. Always turn off the power to your furnace before attempting any checks or repairs. This prevents the risk of electrocution.
- Inspect the Pressure Switch Hose
- Remove the pressure switch hose and examine it for any signs of damage or blockages. Any damage or obstruction can affect the pressure switch’s performance.
- Reinstall the Hose
- Check the hose port for debris or obstructions, clear them out, and then carefully reinstall them. Ensure a secure and correct fit to avoid any leaks or loose connections.
- Check the Ventilation
- Inspect the furnace’s ventilation slots on the cover. If you find any debris, clean the vents thoroughly. Proper ventilation is crucial for the furnace’s operation and for the pressure switch to work accurately.
- Conduct the Pressure Switch Test
- Disconnect the wire connectors from the pressure switch terminals. Use a multimeter to test for resistance. Connect each tester probe to one of the switch terminals. A functioning pressure switch should show a reading of 0 or close to it. If the reading is higher, it indicates a malfunction, and the switch may need replacement by a professional.
- Test the Furnace Operation
- If the pressure switch reading is satisfactory (0 or close to it), reinstall the access panel and power up the furnace. Observe the furnace’s operational capabilities to ensure it’s functioning as expected.
By following these steps, you can effectively assess the condition of your Goodman furnace’s pressure switch. If you are unsure or uncomfortable with the process at any point during the testing, or if the issue seems more complex, it’s advisable to consult a professional. Regular testing and maintenance of your furnace can prevent many common issues and ensure it operates efficiently and safely.
Steps to Replace Goodman Furnace Pressure Switch
Replacing a pressure switch in your Goodman furnace is a task that requires some technical understanding and comfort with handling HVAC components.
If you’re confident in your DIY skills and have the necessary tools, here’s a step-by-step guide on how to replace the pressure switch in your furnace:
- Safety First
- Before you begin, ensure the furnace is completely powered off. This is crucial to avoid any electrical hazards.
- Locate the Pressure Switch
- The pressure switch is typically a small, round component connected to the furnace by a rubber tube and electrical wiring. It’s often found near the draft inducer motor.
- Take a Photo for Reference
- Use your phone to take a picture of the pressure switch setup. This will reference how the wires and hose should be connected to the new switch.
- Disconnect the Hose and Wires
- Carefully disconnect the rubber hose and the electrical wires from the old pressure switch. Be gentle to avoid damaging the connectors and tubing.
- Remove the Old Pressure Switch
- The pressure switch may be secured with screws. Use a screwdriver to remove these screws and gently remove the old switch.
- Install the New Pressure Switch
- Position the new pressure switch where the old one was and secure it with screws. Ensure it’s firmly in place, but avoid over-tightening, which could damage the switch.
- Reconnect Hose and Wires
- Refer to the photo you took earlier to correctly reconnect the rubber hose and electrical wires to the new pressure switch.
- Test the Furnace
- Once everything is reconnected, turn the power back on and test the furnace for normal operation. Listen for the furnace to start and check that it reaches the set temperature without shutting off prematurely.
Tips and Precautions
When replacing the pressure switch in your furnace, it’s important to adhere to certain tips and precautions to ensure a successful and safe repair:
- Choose the Right Replacement: Ensure the new pressure switch is the correct model for your specific furnace. Using the wrong switch can lead to furnace malfunctions.
- Handle with Care: Pressure switches are sensitive components. Handle them carefully to avoid any damage.
- Seek Professional Help if Needed: If at any point you feel uncertain or encounter complications, it’s advisable to stop and seek the assistance of a professional HVAC technician. Furnace repairs can be complex and sometimes require specialized knowledge and tools.
By following these tips and precautions, you can ensure a safer and more effective pressure switch replacement process. Remember, the goal is not just to fix the immediate issue but to ensure the long-term reliability and safety of your furnace.
The Bottom Line
In conclusion, troubleshooting a pressure switch stuck open on a Goodman furnace is a task that requires careful attention to detail, a basic understanding of furnace mechanics, and a commitment to safety. By methodically going through the steps of checking the pressure switch hose, ensuring clear venting, and possibly testing or replacing the pressure switch itself, you can address one of the most common issues faced by furnace owners.
However, it’s important to remember that while some aspects of this process can be handled as DIY projects, others may require the expertise of a professional. The key is knowing your limits and seeking help when necessary to ensure your furnace runs efficiently and safely.
Regular maintenance and prompt attention to issues like a stuck open pressure switch will keep your Goodman furnace in good working order, providing reliable warmth and comfort in your home.
