Why Is My Goodman Furnace Pressure Switch Stuck Open?
If your furnace is showing an open pressure switch error, don’t panic! While the pressure switch is an important safety feature, an open pressure switch is usually an easy and inexpensive fix.
An open pressure switch can be the result of a disconnected pressure switch hose, blocked venting, or a failing pressure switch. By fixing these issues, your pressure switch should begin to work how it should. If it doesn’t, you may need to replace it or hire a specialist.
In this article, we will discuss what exactly a pressure switch is and the common issues that could leave it stuck open. By fixing these problems, you should restore your switch so that it can work like new!
What Is A Pressure Switch?
During the combustion process, your furnace creates excess gases that you don’t want sticking around and filling your home. The pressure switch is a safety feature on your furnace that helps keep this unpleasant situation from happening.
The pressure switch ensures that these gases exit your home and don’t get cycled back into the system, which is known as back drafting. Backdrafting can release carbon monoxide into the air and cause mini-explosions inside of your furnace. Of course, these are both situations that you certainly don’t want to happen, so it’s critical to investigate immediately!
If the pressure switch senses negative pressure from the draft inducer motor, it will shut the furnace down. Obviously, when this happens, your furnace is no longer creating any hot air. This is an especially big problem during the cold winter months, so it’s essential to quickly solve the issue.
The Steps Your Pressure Switch Takes To Prevent Backdrafting
- Gases are sucked out through the flue. During the combustion process, your furnace creates gases. There are many gases, like carbon monoxide, that you do not want to remain inside of your home. These gases are sucked out by a draft inducer motor then sent out of your home through a flue pipe.
- Your pressure switch makes sure the draft inducer is working correctly. If so, the pressure switch will close and remain on.
- The pressure switch opens. If your pressure switch identifies an issue with the draft inducer motor, it will open. When your pressure switch opens, this turns off the furnace and prevents it from lighting.
On a positive note, an open pressure switch means that dangerous gases are not entering your air. The open switch shows that your furnace’s safety features are operating correctly and alerting you of potential issues!
Common Issues That Cause A Pressure Switch To Stay Open
There are several common issues that will cause a pressure switch to stay open. While this can be frustrating, the solution to the problems is easy to fix. There’s no need to hire a professional, as all these solutions are very DIY friendly.
Disconnected Pressure Switch Hose
The pressure switch is connected to the draft inducer motor by a hose. If this hose is disconnected or damaged somehow, the pressure switch can’t get an accurate reading, which causes it to open.
Although it may be easy to determine if the hose is detached, it isn’t easy to reattach it. If the connection hose is disconnected, you should call a professional to reattach or repair the hose.
You may have a blocked flue pipe that is preventing gases from properly exiting your house. If this is the case, your pressure switch will open. This is a fairly common problem as flue pipes can become easily clogged with debris from outside.
Luckily, flue pipes can be easily cleaned, and they are usually located on the roof or side of the house. Once you clear away all of the reachable debris, turn on your furnace again to see if this has fixed the problem.
If this doesn’t solve the issue, your best bet is to call a professional. There may be a clog deeper in the flue pipe that isn’t easily accessible.
Failing Pressure Switch
If neither of the above reasons seems to be causing the issue, you most likely have a problem with your actual pressure switch. It is likely that the switch is old, has dust buildup, has a stiffened pressure switch diaphragm, or there may be holes or tears in the diaphragm.
If you find that the problem is with the actual pressure switch, then you will most likely need the help of an expert. You should call a professional to deal with this issue and replace the pressure switch if necessary.
How To Test A Furnace Pressure Switch
If you want to see how your furnace pressure switch is operating, you can test it yourself. This DIY task requires an intermediate skill level.
Tools You Will Need for the Job
To test your furnace pressure switch for electrical failure, you will need:
- Turn off the power to your furnace. You never want to mess with any electrical components while the electricity is running through the lines. This can cause electrocution and death.
- Check the switch. Remove the pressure switch hose and check it for damage or obstructions.
- Reinstall the hose. Check the hose port for obstructions, remove any debris, and reinstall the hose.
- Check the ventilation. Check the ventilation slots on the furnace cover for debris and, if necessary, clean the vents.
- Test the pressure switch. Disconnect the wire connectors from the switch terminals on the pressure switch. Use the multimeter to test for resistance by touching each tester probe to the switch terminals. A proper switch reading should be 0 or closer to 0, so if the reading is higher, it needs to be replaced by a professional.
- Test the furnace. Reinstall the access panel if the switch reading is 0 or close to 0. Run the furnace to test its operational capabilities.
Types Of Furnace Pressure Switches
Furnace pressure switches vary from furnace to furnace. There is one pressure switch in single-stage conventional furnaces. In these furnaces, one hose connects the pressure switch to the draft inducer fan.
There is one pressure switch with two hoses in single-stage condensing furnaces. One hose senses the pressure at the draft inducer fan. The second hose senses proper venting pressure at the condensate collector box.
There are usually two pressure switches on two-stage furnaces. Two-stage furnaces have both high and low levels of heat output that allow for even heat distribution in different seasons.
How Much Does a New Pressure Switch Cost?
Replacing a pressure switch is an inexpensive fix. A single-stage pressure switch usually ranges in price between $20-$50. A two-stage pressure switch runs between $30-$75.
How To Replace Your Pressure Switch
You can remove and replace your furnace pressure switch by following these steps:
- Turn your furnace off. You should also unplug it, so there’s no chance of any accidents happening while you’re working inside of the combustion chamber.
- Remove the panel. Unscrew the panel from the combustion chamber.
- Unplug the wires. Disconnect the wires connecting the pressure switch to the unit.
- Detach the vacuum tubes from the unit.
- Remove the old pressure switch. Remove the screws that attach the pressure switch to the draft inducer motor.
- Install the new switch. Attach the new switch to the motor.
- Reconnect the inner workings. Connect the wires and vacuum tube to the new pressure switch.
- Replace the panel and restore power. Replace the combustion chamber panel and turn the furnace back on.
If these steps prove too difficult, it is in your best interest to hire a professional to replace the pressure switch. If you replace your pressure switch and there are still problems, definitely call a professional to diagnose what is wrong with your furnace.
Should a pressure switch be open or closed?
A pressure switch should be closed when working correctly. An open pressure switch indicates that there is a problem with the furnace.
Where is the pressure switch located on a Goodman furnace?
The furnace pressure switch is located near the draft inducer motor on your furnace.
What does it mean when your furnace is in lockout mode?
If your furnace detects an unsafe condition, it will cease operation and issue a command that stops any later attempted ignitions. After several attempted restarts, the furnace will go into lockout mode.
It won’t try to run again until the furnace is manually reset. System lockouts can occur because of a faulty pressure switch.
Your furnace pressure switch may be open because of a disconnected pressure switch hose, blocked venting, or a failing pressure switch. Fixing this usually proves to be easy and inexpensive.
When your furnace is in use, gases are created in the combustion chamber. The pressure switch prevents these poisonous gases from leaking into your house. You can test your pressure switch’s effectiveness with a multimeter and replace the switch easily if needed.
There are several types of furnace pressure switches that can replace your old one. Each type goes with a specific type of furnace to make sure your air is clean. A properly functioning pressure switch will keep you breathing easy!
Stacy Randall is a wife, mother, and freelance writer from NOLA that has always had a love for DIY projects, home organization, and making spaces beautiful. Together with her husband, she has been spending the last several years lovingly renovating her grandparent's former home, making it their own and learning a lot about life along the way.
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