Thermostat Not Working? Read our 2023 Quick Fix It Guide!

thermostat not working

Is Your Thermostat Not Working Properly? 

A faulty thermostat is notorious for making you think you have a more serious issue with your air conditioner. 

Your thermostat is the brain of your HVAC system both in summer and winter.

It communicates the temperature information inside your home to the HVAC unit itself.

It tells it to cool or to heat based on your thermostat settings. 

Listed below are the most basic problems and solutions related to a malfunctioning thermostat.

This will help you understand the common thermostat problems your HVAC system may face during uncomfortable weather. 

These thermostat problems and solutions also apply if you have a heat pump.

⭐ Troubleshooting the Most Common Thermostat Problems

⚒️ Wrong Thermostat Setting

checking thermostat settings

You would be surprised by what we see on service calls.

For example, sometimes your HVAC system isn’t working correctly because the thermostat isn’t set correctly.

Most homeowners tend to conclude that something wrong is happening when it could just be their partner not agreeing on the temperature and changing it without their knowledge.

Check the mode

If your air conditioning is blowing hot air and not cold air, check that the mode is set to COOL and not HEAT.

It’s an easy mistake to make, especially if you have a digital thermostat. Also, it’s easy to hit other settings by mistake.

Check the temperature setting

Actually, look at the number on your thermostat. Your AC won’t fire up if there is a higher temperature setting than your current temperature.

Related Reading: Best AC Temperature in Summer?

Thermostat programming

– A thermostat may cause problems because it’s not properly programmed.

You might be running a preset temperature schedule in the wrong modes or connections.

You can fix this by checking the owner’s manual, reprogramming it, and ensuring the functions are set correctly.

⚒️ The Thermostat’s Power Source Is Failing

Your HVAC system won’t work if the thermostat is dead.

If the thermostat’s display is black, it could be caused by dead batteries, poor or loose wiring, or a tripped circuit breaker.

If you have an older thermostat, it might be a blown fuse.

Even low batteries can mess with your thermostat, even if it looks powered up.

To troubleshoot, replace the batteries and check functionality.

If you still have issues, remove the thermostat cover and check the wire connections and electrical components.

Some thermostats have their own power supply and are not powered by batteries.

In this case, be sure to check out your main electrical panel and check you don’t have a tripped breaker.

Phyxter HVAC technician adjusting a thermostat

⚒️ You Have a Dirty Thermostat

If you have replaced your batteries and are still having electrical issues, maybe it needs a clean. 

Dust and other debris can easily make their way into your thermostat.

If it looks dirty inside, remove your thermostat’s cover and use a soft brush and low-pressure compressed air to clean out your thermostat.

If you find loose connections or loose terminal screws, ensure you tighten them up with the right screwdriver.

If you find corrosion, you may need to replace your thermostat.

⚒️ The Thermostat Is Installed in the Wrong Location

If your thermostat is mounted in the wrong location, it may sense false information to keep your home comfortable.

If your thermostat is mounted anywhere in direct sunlight, it will sense that it’s warmer based on radiant heat rather than the ambient temperature in your home.

To fix this, remount your thermostat in a shaded area near the room that you use the most frequently.

Also, ensure it’s not mounted anywhere that may have higher airflow, such as doors, registers, vents, or windows.

⚒️ The Thermostat Isn’t Level

checking thermostat is level

Are you having issues with temperature discrepancies?

It might be because your thermostat is not mounted level.

Many thermostats are fitted with a mercury switch, and this must be level to work correctly

To remedy this thermostat issue, loosen the mounting hardware and use a carpenter’s level to check it.

🛑 NOTE: If you have an older thermostat containing mercury, ensure you dispose of it correctly.

You can learn more about mercury disposal through the EPA here: epa.gov/mercury/mercury-consumer-products

⚒️ You have a Bad Thermostat

Sometimes you just can’t fix a problem if the unit is bad and your thermostat fails to reach the desired temperature.

You can check the calibration by mounting a glass thermometer next to your thermostat and check for discrepancies.

If, after 15 minutes, your thermostat is wrong more than one degree, your placement is good, and the unit is level, it’s probably time for a new one.

⚒️ When to Replace Your Thermostat

really old thermostat

There are plenty of reasons why you should replace your thermostat, but the two main reasons are age and that it’s improperly paired with your current HVAC system.

Firstly, your thermostat might just be suffering from old age.

After a while, connections become loose, wires corrode, and electronic components start to degrade.

Replacing your thermostat is also great in helping manage your HVAC systems’ energy efficiency. 

The second problem could be the improper pairing with the rest of your cooling system.

Maybe you had some upgrades over the years, and now you have a mismatch with either your cooling or heating system.

It’s important that your thermostat communicates correctly with your entire system.

Understand what you want from your HVAC system in terms of capability and speak with your local HVAC contractor.

They will recommend a new thermostat that matches your requirements and compatibility with your cooling system.

Aesthetics can come into play.

If you are a keen DIYer constantly upgrading your home and want an old mechanical thermostat with a round dial mounted on your wall, go right ahead, though it might not be the right choice.

Digital thermostats have come a long way in looks and functionality and are pivotal in improving your home’s energy efficiency.

According to Nest, the Nest Learning Thermostat saved 10% to 12% on heating and 15% on cooling.

So get rid of that old thermostat and join the rest of us in the 21st century.

⭐ Time to Call a Professional

Phyxter Approved Logo on Service Truck

If you find that your thermostat is still not working, don’t panic.

The above points are simple steps you can take to troubleshoot and fix the issue yourself.

With a little bit of effort, you can have your thermostat back to its normal functioning in no time.

So don’t let a faulty thermostat ruin your comfort, take control and fix the issue today!

That’s why we preach to our customers that checking your thermostat is part of your regular maintenance schedule to avoid problems before they get expensive.

If you have gone through the above instructions and still experience thermostat problems and can not maintain your desired temperature, it’s time to call an HVAC professional.

If you live in the Central or North Okanagan area, then check out Phyxter Home Services.

We provide a range of HVAC services, from air conditioner installation and furnace replacement to thermostat repair and beyond.

We pride ourselves on the best customer service in the market, and our only goal is to ensure you and your family are comfortable at an affordable price.

Dealing with other common AC problems? Check out: Top 18 Common AC Problems and Solutions.

Having problems with your furnace in winter? Check out: Homeowners Guide to DIY Furnace Repair: 16 Most Common Problems & Solutions

Jake Gibson

CEO @ Phyxter and HVAC Guru

About our blog

Phyxter (pronounced Fix-ter) is a national home services brand specializing in Residential HVAC, Electrical and Plumbing solutions.

Phyxter is laser-focused on writing the best articles and guides to empower homeowners to get the best out of their homes.

We hope you enjoy it!

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