A furnace pressure switch is amongst the most important components of a furnace. If it malfunctions, your furnace will not work properly. There could be several reasons contributing to the issue and for some you may need to involve heating repair services. Therefore, we are going to discuss the pressure switch in detail and what you can do to troubleshoot any related problems.

Why Won’t My Furnace Light?

It is quite often that homeowners come to find out that the furnace won’t light due to the igniter or gas valve issue. Surprisingly, this is not the case every time. Although these factors do contribute to such problems, but there is one in particular that is often overlooked and misunderstood – the pressure switch.

This is why it is important for you to understand how the pressure switch works and what you can do to fix the issues. In simple words, a furnace pressure switch is a component, which allows power to pass through it. When the power switch is open, the power is not transferred. Whereas, if it is closed, the power can pass.

If your furnace has a light switch, it will not turn on until you flip the switch and allow power to pass through. However, in the case of a power switch, it utilizes air pressure or suction. The suction is produced by the draft inducer or inducer fan. Ultimately, when the switch is pulled close, the power is passed onto the next component, which happens to be the igniter.

The Purpose Of Your Furnace’s Pressure Switch

Technically, the pressure switch of your furnace acts as a safety feature. It is designed to ensure that the furnace drafts properly. If for some reason, the furnace is not drafting properly, the unit will not operate efficiently and risk an explosion due to the accumulation of unwanted gasses inside the heat exchanger. This is why, if the pressure switch does not detect a sufficient amount of suction, it will not allow the unit to ignite.

What Are The Causes Of Pressure Switch Failures?

As mentioned earlier, there are several reasons contributing to pressure switch failures. Even though it might be a bit tricky to diagnose a faulty pressure switch, but you should check blockage in the inducer fan as well as bad/loose wire connection.

In addition to that, you should check any blockage in the flue or chimney in addition to water built up in the inducer fan housing.

What Are The Signs Of A Faulty Furnace Pressure Switch?

Even if your pressure switch has gone bad, it will continue to work since it is designed for safety. This means that the furnace will not work and you will just be receiving room temperature air from the vents. It might be that the furnace is going into lock mode. This means that either the igniter or pressure switch has gone bad and you will only notice it when the vents begin to throw room temperature air.

What To Do When Your Pressure Switch Fails?

Even though we have briefly covered the potential problems related to the pressure switch and the inducer fan, but there are several other tips to consider as well that might help solve the issue without incurring any costs or using specialized tools.

To begin with, once the unit is up and running, meaning the inducer has run for around 10-30 seconds, you should listen to the sound of the gas valve “clicking”. If the pressure switch does not work, the gas valve will not open so the clicking of the gas valve means that the pressure switch is working fine. It might be that the igniter is the problem.

However, if you don’t hear the clicking noise, notice if you can hear anything rattling around in the inducer fan. You might be able to remove it. But if you hear the motor whining or grinding, you will need to replace it with a new part.

Final Word

Concluding, a pressure switch will throw several signs at you when it is going bad. However, you need to be observant and keep a close eye on the indicators. If the problem is complicated and tricky to diagnose, call in furnace repair services for help. topac