Anatomy Of A Repair: Diagnosing A Pressure Switch Error Code

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When the heat is rising to record-breaking levels, it can be really tough to stay cool. This summer, I found that my air conditioner had trouble keeping up with the temperatures. It wasn't that the AC wasn't working, it was just that I couldn't seem to get my house cooled down as much as I wanted. I worried that I would have to replace the whole AC system. Luckily, I have a good friend who works as an HVAC contractor. He took a look at my system and gave good news -- it didn't need to be replaced. Instead, he shared a lot of tips for helping my air conditioner work more efficiently, as well as some ideas to help supplement the AC and keep the house cooler. I'm using those tips to create this blog to share ways for all of us to keep cool on the hottest days.

Anatomy Of A Repair: Diagnosing A Pressure Switch Error Code

1 February 2022
 Categories: , Blog

There's a world of difference between do-it-yourself solutions to HVAC problems and professional repairs. While many small things around the home are easy to fix, your gas furnace can be a surprisingly sophisticated piece of machinery, and it often requires careful diagnosis. Not taking this complexity into account can lead to failed repairs or wasted money on unnecessary parts replacements.

This guide will go over the anatomy of a seemingly straightforward exhaust fan repair and explain some potential pitfalls that can lead to an inaccurate diagnosis and wasted money.

What Can An Error Code Tell You?

Your furnace's drat inducer (or exhaust fan) pulls combustion gases through your flue and outside of your home. The control board uses a pressure switch to sense the vacuum created by this fan, turning the furnace on only after proving that the draft inducer is functioning correctly. Modern furnaces will typically trigger a pressure switch error code if they can't detect this vacuum.

Unfortunately, this error code won't tell you the whole story. Just as with the check engine light in your car, the error code only alerts you to erroneous sensor data. However, there may be several underlying causes. The lack of pressure may be due to a failing draft inducer motor, a wiring problem, or even a faulty pressure switch reporting inaccurate data.

How Will a Professional Diagnose Your Problem?

A professional HVAC technician will do more than read the error code and immediately condemn the draft inducer motor. Instead, they will use the error code as a starting point before confirming the problem. Every technician's diagnostic process will be different, but they will usually ensure that the draft inducer has power and test the pressure switch for correct operation.

These steps are necessary because they can reveal deeper issues within your furnace. For example, it's possible to receive a pressure switch error code even if your switch and inducer motor are both working correctly. This situation can occur if there's an issue with your furnace's wiring or control board. Blindly replacing either part without further testing will waste time and money.

While pressure switch error codes are relatively straightforward problems, they still require a thorough understanding of gas furnace operation and startup sequences. Without this knowledge, it's easy to miss small details or even overlook the actual cause of the problem. Relying on a trained and experienced technician sidesteps these issues and ensures a quicker and more cost-effective heating repair.