pressure switch

During the colder months, when furnaces are used often, the furnace pressure switch is very important for ensuring the safe operation of your home’s heating system. Knowing how to fix and deal with the issues that arise in a pressure switch can help homeowners minimize having to deal with dangerous situations and emergency furnace problems.

In this article, we’re showing you how to deal with the most common issues that your furnace pressure switch can face with a quick and easy troubleshooting guide. Read along to find out everything about it.

Signs of Malfunctioning Furnace Pressure Switches

Furnace Fails to Start

The inability of the furnace to begin its start-up process is a clear indicator of a malfunctioning pressure switch. The pressure switch senses the air pressure present in the furnace and is in charge of assuring safe starting conditions. In the case that there is a pressure switch failure, it may inaccurately sense the air pressure, which will prevent the furnace from starting.

Erratic Furnace Cycling

If your single-stage condensing furnace starts up and then stops too often or cycles on and off more than normal, it could be because the pressure switch isn’t consistently detecting the correct negative air pressure. This can lead to erratic cycling. This intermittent behavior is frequently an indication that the switch lacks the capability to sustain an uninterrupted operation.

Continuous Operation

On the other hand, the furnace might run continuously if the pressure switch doesn’t respond when closed. This causes the furnace components to be stressed and leads to unnecessary increases in energy usage.

Unusual Noises

If you hear an unusual sound, like clicking, coming from the switch area, it could be a sign of a mechanical problem with the switch mechanism.

Diagnostic Error Codes

Many newer furnaces come equipped with built-in diagnostic systems that show codes for diagnostic errors on the panel. An obvious sign of possible malfunction is when your system displays a pressure switch fault.

If you care about the efficiency and safety of your heating system, you must learn to recognize the symptoms of a broken pressure switch in your furnace. If your pressure switch is not working properly, you might observe the following:

comfortmaker furnace troubleshooting

Troubleshooting Steps for Furnace Pressure Switch Issues

To troubleshoot a furnace pressure switch, you need to follow a set of steps to find and fix problems that could stop the furnace from working safely and efficiently. Listed below are specific procedures that specialists and homeowners can take to identify and, if necessary, repair issues with the furnace’s pressure switch.

Turn off the power to the furnace before you begin troubleshooting. Make sure the furnace is turned off entirely by finding the main power switch or circuit breaker. Avoiding electrical risks and accidents is of utmost importance when inspecting the furnace's components.

Take off the furnace access panel, look for the pressure switch, and then disconnect switch located. The pressure switch is usually located near the draft inducer motor, which is typically round-shaped. Find the switch and look for cracks, burns, corrosion, or other visible indications of wear and tear. If the switch requires replacing, you may usually tell by looking for these physical symptoms.

Make sure the hose that is attached to the pressure switch is securely fastened at both ends and that it is not cracked, clogged, or otherwise worn. Carefully disconnect the clogged hose port and check inside for anything that can restrict airflow, such as debris or obstructions. To make sure the switch is getting accurate pressure readings, repair the hose if it's damaged.

Inspect the connection point between the hose and the switch and clean it using a tiny screwdriver or an equivalent instrument. Get rid of anything that could block the pressure gauges, like accumulation or debris. To avoid additional problems, be cautious not to damage the switch body.

Inspect the flue pipe and vent pipe, as well as the rest of the venting system, for any blockages or leaks. A change in the negative pressure levels measured by the switch can cause the furnace to operate improperly if these pipes get obstructed. To make sure exhaust fumes can escape properly, check that all pipes are clear and in good shape.

Check for corrosion and tightness in all electrical connections pertaining to the pressure switch. Intermittent switch operation can be caused by connections that are loose or corroded. Remove any corrosion from the terminals and secure any loose connections.

Disconnect the pressure switch's electrical connections. Get a multimeter ready by configuring it to measure continuity and connecting the probes to the terminals of the switch. When the furnace is turned on, a properly working switch should display continuity. There may be a need to replace the switch if the multimeter indicates a lack of continuity.

If the first tests don't yield any results, you may attempt to simulate the pressure variations that occur when a furnace is normally turned on and off. One way to do this is to use a manometer to apply pressure to the switch by hand. Keep an eye on the output of the switch to make sure it turns on and off at the precise pressures recommended by the furnace's maker.

For further instructions on how to diagnose the furnace and what parameters to use when checking the pressure switch, see the service manual. For proper troubleshooting, it may be necessary to adhere to the specifications or procedures that are specific to each kind of furnace.

If the pressure switch still turns out to be faulty after running all the tests, use the manufacturer-recommended replacement part. After installing the replacement switch, double-check that it is securely in place.

Furnace Pressure Switch Maintenance Tips

If you want your heating system to work properly and safely, you must keep the pressure switch on the furnace maintained. For optimal performance of this essential part of the furnace, follow these steps and tips:

On a frequent basis, check the pressure switch and its parts for damage or debris buildup. Carefully wipe the switch down with a delicate brush or cloth, taking extra care not to scratch any delicate components. This guarantees the switch can detect pressure changes precisely and without interference, and it also increases its lifespan.

Due to the constant movement of the furnace, the connections at the pressure switch can eventually become loose. As part of your regular inspections, check the terminals for corrosion and ensure that all wiring is tight. To prevent water and grime damage, secure any loose connections and think about using a non-conductive sealant.

The functionality of the pressure switch is dependent on the state of the hose that connects to it. Make that there are no holes, damage, or splits in the hose. If the hose is damaged in any way or if you discover anything within that could interfere with the flow of air or the pressure detection, you should replace it.

Make an appointment with a licensed HVAC expert like Comfort Union to check on your furnace once a year. To make sure everything is in good functioning order, they will inspect the pressure switch in addition to other components such as the draft inducer motor, burners, and venting systems. Unexpected failures during high-use periods might be lessened with this preventive maintenance.

What should you do when a furnace pressure switch doesn't work, even after troubleshooting?

Calling a professional is highly important if you consistently face issues with your furnace pressure switches. Not taking good care of the component can lead to major issues and it must be handled by an HVAC technician.

At Comfort Union, we provide expert services for all kinds of heating system issues – be it with the main device or its parts. Contact us to learn more details about our services!

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