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.
Troubleshooting Goodman Furnace Pressure Switch Stuck Open
A problem with a pressure switch stuck open, indicates a problem elsewhere in the Goodman furnace that needs to be addressed.
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.
Sometimes the pressure switch itself is defective and can 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.
Cost to replace Goodman furnace pressure switch:
- Single-stage Goodman furnace the price range between $25-$50.
- Two-stage furnace, pressure switch price rangen between $40-$75.
You can replace your furnace pressure switch by following these steps:
- Turn your furnace off.
- Remove the panel.
- Disconnect the wires.
- Remove the old pressure switch.
- Install the new switch.
- Reconnect the wires.
- Restore the panel and turn ON your furnace.
The Bottom Line
Troubleshooting a pressure switch stuck open on Goodman furnace can be tricky. With a complex system and commonly misdiagnosed problems, it’s important to consult a professional HVAC Technician if your Goodman furnace stops working or blowing cold air.