How Do You Fix The Centrifugal Switch That Is Stuck Open On Our Coleman Evcon Forced Air Furnace

If you find yourself in the unfortunate situation of a furnace pressure switch stuck open, don't worry. In most cases, there are some simple things that can exist done to fix the problem and get your furnace back up and running smoothly.

In this article, I'll go over what to do when your furnace's force per unit area switch is stuck open up. I'll too embrace how to troubleshoot your furnace'southward pressure switch, and how to supplant your furnace's pressure switch.

What to do when your furnace'south pressure switch is stuck open

Starting time, it's important to effigy out why your furnace pressure switch is stuck open. Luckily there are some things that you can check before replacing the switch.

Check for debris or blockage in the flue vent

The #1 reason for a pressure level switch to be stuck open is blockage in the furnace exhaust vent.

Blockage in the exhaust vent will prevent a furnace from heating, or shut it down completely.

Here are a few common sources of blockage in an exhaust vent:

Branches or leaves
Bird's nest
Soot buildup
Snowfall

If you run across whatsoever debris in the exhaust vent, and so you'll need to clean it out. Go where the frazzle vent opens up exterior your home. Next, search for any signs of blockage in the vent.

If you notice a blockage, and so you need to remove it. Then your pressure switch should start working correctly again.

Brand sure the inducer fan is starting

The inducer fan is responsible for venting the frazzle gases outside your home. If the inducer motor in your furnace is non starting, then the pressure switch won't shut. In fact, the entire purpose of the pressure level switch is to ensure that the inducer fan is working properly.

About times, you'll be able to hear or run across the inducer fan turn on. And then that'south one style to know if it'due south working properly.

For more avant-garde troubleshooting on furnace inducers, check out my article beneath:

Bank check the pressure level switch hose

The pressure switch hose connects the pressure switch to the exhaust vent in your furnace. The hose is needed so the force per unit area switch tin can detect the pressure in the exhaust vent.

If the hose is damaged, cracked, or disconnected, then the pressure switch will stay open and your furnace won't heat up.

If the hose is cracked or damaged, so it needs to exist replaced.

If the hose is asunder, and then you will need to reconnect it.

If you accept a 2-stage furnace then y'all will have two force per unit area switches that you lot demand to check.

Also, yous need to check for moisture build-up inside the hoses if you take a loftier-efficiency furnace. Empty out any water from the hoses to ensure that the pressure switches can function properly.

Location of pressure switch in a furnace

How to troubleshoot your furnace'south pressure switch

If you lot checked everything above but the pressure switch is all the same non working, at that place are two dissimilar tests that you tin do.

Both of these tests require a multimeter, so exist sure you have one earlier proceeding.

Fluke 116 HVAC Multimeter

The Fluke 116 is ane of the best multimeters for diagnosing and troubleshooting bug in a residential furnace.

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How to examination for continuity across pressure switch terminals

The starting time thing that you should do when troubleshooting a pressure switch is to test for continuity across its terminals.

To test for continuity across the pressure switch, follow these steps:

Turn off power to your furnace and open its access panel.
Disconnect the 2 wires from the pressure switch.
Touch the two terminals on the pressure switch with your multimeter leads. Employ your multimeter on the resistance (Ω) or continuity setting to check if the pressure switch is airtight. If the furnace is off, then the pressure switch terminals should be open, so y'all should encounter open line (OL) on your multimeter.
Turn on power your furnace and set your thermostat to "HEAT" style. The furnace'due south inducer motor should showtime upward.
While the inducer fan is running, test the pressure switch in the same way that you lot did previously. Still, this time, y'all should read a short circuit on your multimeter (or a depression amount of resistance such as 0 or one Ω). If your multimeter is in continuity fashion, it will beep.
If your pressure level switch passes all the tests above, then there is zippo wrong with your pressure level switch! Go ahead and reconnect the wires to the pressure level switch terminals and close upwardly your furnace.

How to examination for voltage across pressure switch terminals

Another method to test a furnace pressure switch is by measuring the voltage beyond its terminals.

To exam for voltage across the pressure switch, follow these steps:

Turn on your furnace and set your thermostat to "OFF" mode.
Open your furnace's access panel.
Turn your multimeter on to the AC voltage setting (V~).
Bear on the two multimeter probes to the two terminals on the pressure switch. You lot should read somewhere between 24-28 volts. This means that the pressure switch is open.
Set your thermostat to "Oestrus" manner.
Bear on the two multimeter probes to the two terminals on the pressure switch. You lot should read somewhere betwixt 0 volts. This ways that the pressure switch is closed.
If your pressure level switch passes all the tests above, so at that place is cypher incorrect with your pressure switch! Go ahead and close up your furnace.

How to replace a furnace pressure switch

Replacing the pressure switch on a furnace is not very difficult. You but demand a few basic tools and some time to do the replacement.

The hardest role of replacing a pressure switch is finding a replacement pressure switch. It tin exist difficult to rail down the correct function, especially for older furnaces.

I recommend looking for the office number on the old pressure level switch. It should be printed on the pressure switch itself, or on a sticker. Once you lot find the office number, search for it on the internet. Nearly times you'll be able to find it and buy it online.

To supervene upon a pressure switch in a furnace, follow these steps:

Turn off power to your furnace and open its admission console.
Disconnect the two wires from the force per unit area switch.
Disconnect the hose from the pressure switch. Make a note of which port the hose connects to.
Remove the old pressure switch from the furnace. Most times, you just need to undo a few screws to remove the pressure switch.
Install the new pressure switch inside the furnace. The new pressure switch might come with a bracket that holds it in place. If that's the instance, then you demand to employ the new bracket if it's different than the onetime 1. If it'southward the same type of subclass, experience free to re-use the old 1.
Reconnect the hose to the new pressure switch in the same port that yous removed it from earlier. The hose will connect to the negative port (–) on the force per unit area switch.
Reconnect the wires to the new pressure switch. Information technology does not thing which wire goes where. Nevertheless, if your pressure switch has 3 terminals, and then the wires need to connect to the Mutual (COM) and Normally Open (NO) terminals.
Close up the access panel to your furnace and turn its power back on. Get ahead and test the furnace in "HEAT" mode on your thermostat to make certain everything works correctly.