How Do You Bypass a Pressure Switch?
- Disconnect the two wires attaching to the pressure switch.
- Turn ON the furnace and wait for the draft induce to start up.
- Touch the two wires to jump the furnace. This step closes the switch.
Full Answer
How to fix the pressure switch on a furnace?
Some of the more common reasons I’ve seen furnace pressure switches either fail or not close to allow the rest of the system fire up are:
- A clogged port on the collection chamber to the pressure switch
- An obstruction in the flue
- A diaphragm that’s ruptured or stuck
- The pressure switch hose is damaged
- The pressure switch hose has water in it
Can you bypass furnace limit switch?
Yes, you can temporarily bypass the temperature limit on your furnace. For example, you can bypass the limit switch when trying to find out why your furnace shuts down too frequently or runs but doesn’t blow warm air.
How do you test a furnace pressure switch?
The steps are as follows:
- The switch wires have to be removed first.
- Touch the two switch wires with the multimeter leads. ...
- The furnace will be turned on next. ...
- Now commence blowing air out of the vent so that a vacuum is created.
- The vacuum makes the diaphragm pull in, and hence the switch is closed.
- Use the multimeter to check if the switch closes.
How to replace the gas control valve on your furnace?
Things You'll Need
- Adjustable wrenches (2)
- Masking tape
- Slotted screwdriver
- Pipe wrench
- Gas-approved pipe thread compound
How do you bypass the pressure switch on a furnace?
How to Jump a Furnace Pressure SwitchDisconnect one of the two wires from the pressure switch.Connect it to one end of your jumper wire.Turn on the furnace. ... Connect the other end of the jumper wire to the other wire on the pressure switch.Let it run for a few minutes.
Is it safe to bypass a pressure switch?
BYPASSING THE PRESSURE SWITCH IS NOT A REPAIR It is simply an attempt to troubleshoot the furnace by isolating what might be causing the problem. Any attempt to bypass the system should only be done by an HVAC technician with the proper training and test equipment.Dec 3, 2021
How do I know if my furnace pressure switch is bad?
1:1814:26How to Test Pressure Switch on a Furnace - YouTubeYouTubeStart of suggested clipEnd of suggested clipAt your switch without the inducer motor running that means your switches stuck closed. And that's aMoreAt your switch without the inducer motor running that means your switches stuck closed. And that's a bad switch.
Can you bypass the flame sensor on a furnace?
Yes. You can bypass the flame sensor. However, if you do so, you can't manually light your furnace, and you've got to have proper bypassing safety measures in place. But it's advisable not to bypass the flame sensor.
What is the purpose of a pressure switch on a gas furnace?
A furnace pressure switch is an automatic safety feature located near the motor. It shuts the furnace down if it senses negative pressure created by the draft inducer motor. This protects your home from dangerous backdrafting, which is when exhaust fumes are reintroduced into the system.Jan 25, 2018
How do you reset a pressure switch?
Instructions to Reset Low Water Cut Off Pressure SwitchLocate pressure switch. ... Locate the reset lever. ... Locate the AUTO / START / OFF positions. ... Locate the pressure gauge. ... Move the reset lever up into the start position and hold it there.
Are pressure switches interchangeable?
Different furnaces may have different types of pressure switches in them. Based on the size of the unit (meaning heat output capability, not the physical dimensions), the amount of suction the pressure switch requires to work will vary.Feb 28, 2022
How do you troubleshoot a pressure switch?
0:032:14Pressure Switch Troubleshooting - YouTubeYouTubeStart of suggested clipEnd of suggested clipTake the pressure switch tubing off the pressure switch. Take your tea tea into your pressure switchMoreTake the pressure switch tubing off the pressure switch. Take your tea tea into your pressure switch tubing. And then put the other end. Back on your pressure switch.
THE ROLE OF A PRESSURE SWITCH
The pressure switch plays a vital safety role. It’s normally located near the furnace motor and is designed to sense negative air pressure which causes dangerous back drafting, a leading cause of carbon monoxide poisoning. This system is also designed to protect against gas leaks. In either situation, the system will shut the furnace down.
BYPASSING THE PRESSURE SWITCH IS NOT A REPAIR
On some occasions this system can be faulty or fail entirely, meaning the furnace won’t work. The problem is that homeowners often want to try and diagnose this on their own or bypass the switch in an attempt to restart the furnace. The first thing they need to realize is that bypassing this system is not meant to repair a furnace.
TESTING A PRESSURE SWITCH
Testing a pressure switch is not something most homeowners are qualified to do. It takes an electric multi-tester and the knowledge to use it correctly to measure resistance and voltage. On the plus side, replacing this system is not a huge job for an HVAC technician. It also costs much less than many furnace repairs.
SCHEDULE FURNACE MAINTENANCE
This is also another opportunity to emphasize the importance of furnace maintenance. A technician will test the switch during a visit to your home. It’s just one more way Armstrong Plumbing, Air & Electric can protect your Lubbock, Texas home against a furnace breakdown. Call now to make an appointment for your seasonal furnace maintenance.
WHAT IT IS & WHAT IT DOES
The pressure switch is on a furnace to protect you and your home. Normally located near the furnace motor its vital safety functions include sensing negative air pressure which causes dangerous back drafting, a leading cause of carbon monoxide poisoning. This switch is also designed to detect gas leaks.
BYPASSING THE PRESSURE SWITCH IS NOT A REPAIR
Like any device a pressure switch can fail meaning the furnace won’t work. The problem is that homeowners often want to try and diagnose this on their own or bypass the switch in an attempt to restart the furnace. Climate Control cannot emphasize enough that bypassing the pressure switch is not meant as furnace maintenance or repair.
TESTING A PRESSURE SWITCH
Testing a pressure switch is not something most homeowners are qualified to do. It takes an electric multi-tester and the knowledge to use it correctly to measure resistance (ohms) and voltage. The good news is that replacing a this system is not a huge job for an HVAC technician.
SCHEDULE FURNACE MAINTENANCE
This is another great opportunity to remind you about the importance of furnace maintenance. A Climate Control Company technician will test the pressure switch during a visit to your home. It’s just one more way to protect your Glenwood Springs, Aspen, or Vail, CO home against a furnace breakdown.
Where is the Pressure Switch on a Furnace?
The pressure switch is located near the draft inducer motor of gas-powered forced-air furnaces. It’s a disc-shaped device that’s easily identifiable once you remove the furnace’s front cover.
How to Know if My Pressure Switch is Bad (Symptoms)
Although one of the most common signs is a furnace that won’t start no matter how hard you try, the furnace can refuse to start for many other reasons, including flame sensor-occasioned lockout and a malfunction igniter.
How Do You Test a Pressure Switch?
After verifying one or more of the four issues above, you must test the pressure switch with a multimeter to determine whether the device is broken. Here’s how to proceed;
What Happens if the Pressure Switch Goes Bad?
A bad pressure switch can cause all kinds of issues. Typically, the furnace will not come on no matter how many times you try. And if you try too many times, the furnace may go into lockout.
What Causes a Furnace Pressure Switch to Fail?
The pressure switch can fail for many reasons. However, the most common causes of failure are as follows;
How Long Does a Furnace Pressure Switch Last?
The furnace switch can last many years with regular maintenance. Indeed, many people only replace the switch once or twice over the life of the furnace. Given that an average furnace lasts 15 years, we can say that the switch should last 5-7 years with good maintenance.
When Should I Replace My Furnace Pressure Switch?
You only need to replace your furnace pressure switch if it’s completely damaged or becomes too unreliable. For instance, if you have to reset the switch every two weeks, it might be better to fix the underlying problem. A replacement only costs $75 to $250.

What It Is & What It Does
Bypassing The Pressure Switch Is Not A Repair
- Like any device a pressure switch can fail meaning the furnace won’t work. The problem is that homeowners often want to try and diagnose this on their own or bypass the switch in an attempt to restart the furnace. Climate Control cannot emphasize enough that bypassing the pressure switch is not meant as furnace maintenance or repair. It is simply a...
Testing A Pressure Switch
- Testing a pressure switch is not something most homeowners are qualified to do. It takes an electric multi-tester and the knowledge to use it correctly to measure resistance (ohms) and voltage. The good news is that replacing a this system is not a huge job for an HVAC technician. I’m not going to tell you it’s cheap, but it costs much less than many furnace repairs.
Schedule Furnace Maintenance
- This is another great opportunity to remind you about the importance of furnace maintenance. A Climate Control Company technician will test the pressure switch during a visit to your home. It’s just one more way to protect your Glenwood Springs, Aspen, or Vail, CO home against a furnace breakdown. Call now to make an appointment for your seasonal furnace maintenance. To learn …