How to Check the Temperature of Air Coming Out of Vents in 3 Easy Steps

Learning how to check the temperature of air coming out of your vents is an easy way to test the effectiveness of your air conditioning unit, which could be a great first step in troubleshooting common HVAC problems. Luckily, the process couldn’t be easier! You’ll only need two tools, and it’ll take just 10 minutes of your time or less. Here’s how to get started. 

Prepping to Check the Temperature Coming Out of Vents

It’s important to note your home has supply and return vents. Supply vents are responsible for pushing air from the ductwork into your home. Meanwhile, return vents gather warm, stale air, pulling it through the vents into the ductwork to remove the heat molecules before distributing it again. Because of this, you’ll have two measurements when determining your AC’s effectiveness. 

You’ll start by getting an infrared thermostat if you don’t have one on hand. You can buy these through online retailers like Amazon or your local home improvement store. Generally, you can find these for under $20. You’ll also want to have a calculator on hand (you can use the one on your smartphone) to calculate temperature differences. 

What Causes a Large Temperature Differential?

When there’s a large gap in temperature between air blowing from the vents and the air being pulled in by them, there could be several culprits, such as:

Closed Vents

Closing vents in unused rooms may seem practical, but it actually restricts airflow and can create a temperature and humidity imbalance in your ductwork. Remember, your HVAC system’s design is for your whole home, so using it as designed allows for proper airflow. 

Dirty Air Filter

Air filters catch dust and other airborne particles to prevent them from blowing through your ductwork and into your lungs. However, when an air filter becomes dirty, it doesn’t have the ability to trap as many particles, resulting in dirty ductwork, air vents, and, worst of all, the air you breathe. Replace your air filters as directed. Usually, this is once every one to three months. 

Poor Insulation

Sometimes, a higher differential means your home has insulation issues. If you don’t have them, consider having return air vents installed, as they help balance the humidity and temperature in your home. The cost to add a return air vent runs several hundred dollars. 

DIY vs. Hiring a Pro

You can have an HVAC professional visit your home to do the temperature check for you if you don’t have the equipment or time. On average, an initial service call for HVAC repair can cost between $100 and $250, with any repairs adding to the cost. Meanwhile, you can pick up a well-rated infrared thermostat for less than $20 at most retailers. So, if you have time to spare and the ability to do so, it is much more financially feasible to do this on your own.