Thermostat Not Reaching Set Temperature? Try These Fixes First!

Wondering what’s making your programmable thermostat not reach its set temperature? Well, you aren’t alone, as many homeowners are grappling with this problem. When it’s brutally cold or scorching hot outside, and the room temp shown on the thermostat screen can’t reach what you set it to be, it can be downright frustrating. So, what do you do when the room temperature doesn’t match the thermostat setting? In this post, we’ll take a look at the most common causes of this issue and explore the best solutions for it.

And if going the DIY route doesn't work, it's time to consult an HVAC professional. If you are in the Baltimore metro area and need a quicker and lasting fix or thermostat replacement, SuperTech has your back. And when you move into a new home, make sure you get an HVAC inspection so that you can avoid your thermostat not reaching the set temperature. 

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What Should I Do When My Thermostat's Not Reaching Its Set Temperature?

Recalibrate the Thermostat

If your home or business fails to reach your preferred temperature setting, you may be dealing with a malfunctioning thermostat. Just like any other device, your thermostat may experience technical glitches from time to time. If the program it uses fails, it won't assess the temperatures correctly or give the actual readings. If you would like to learn how to check your thermostat's programming, check out our blog discussing why your thermostat isn't working.

Something else you can do is purchase an AC-specific thermometer: to use it, place it near the thermostat and compare the difference between the two readings. Then use the thermometer readings and the thermostat’s user manuals to recalibrate the thermostat.  

Redo the Thermostat Wiring 

If you just bought a new thermostat and it has been problematic since the installation, the problem could be the wiring. This mostly happens after a DIY installation. Other times, corrosion and lint can build up on the wiring and prevent the current from passing through.

If either of these is the case, call an HVAC technician to inspect and redo your thermostat's wiring. They have the knowledge to get the issue fixed!


Thermostat Not Reaching Set Temperature? Clean the Thermostat 

Sometimes, when the room temperature doesn’t match the thermostat setting, the problem could be dirt buildup on its interior parts.

A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings. To clean the thermostat, remove the faceplate and use a clean, soft brush to gently wipe away the dirt.

As part of our furnace maintenance or air conditioning tune-up, a professional will inspect and clean the wiring of your thermostat so you won't have to worry about this issue!


Keep Your Old-Model Mechanical Thermostat Level

Old round-dial thermostats don’t function properly if their internal components aren’t level. Unlike a common digital thermostat, a mechanical thermostat relies on bimetal springs and a mercury switch that lays horizontally in the device to adjust the temperature. If the switch tilts, it affects the accuracy.

To correct the broken thermostat, remove its faceplate, look for the glass mercury tube, and balance it using a small level. Even better, you can swap out the old, faulty thermostat for a more efficient, modern thermostat.


Reboot The Thermostat If It’s Frozen

If there is an issue with the static electricity around your thermostat, the touch screen may freeze and fail to display any data updates. 

In such a situation, it’s hard to notice that your electronic thermostat isn’t reaching the correct temperature. The best solution is to switch off the device, wait at least 10 seconds, and switch it on.

Replace Your Old Thermostat 

If your device is simply too old, don’t be surprised if the room temperature doesn’t match the thermostat setting.

An old thermostat may fail to read the correct temperatures of your home, sending the wrong information to the furnace, air conditioner, or heat pump. And without accurate information, the heating and cooling unit can’t deliver the specific temperatures you want. So, consider getting a thermostat upgrade.

Relocate Your Thermostat

If your thermostat is located near a window that receives a lot of direct sunlight or is near the fireplace or kitchen, the extra warmth in such areas may trick the temperature sensor into thinking there is more warm air in the house than there is. That means your thermostat can’t sense the general indoor temps correctly. 

If this is the case, have a licensed HVAC expert to relocate it. They will help you find the best spot to relocate it to.

Other Solutions When The Thermostat Fails To Reach The Set Temperature

Sort Any HVAC Equipment Issues That Could Affect The Temperatures

Your thermostat could be working correctly, but your air conditioner or furnace may be the reason why your indoor space is not reaching the set desired temperature. Here are two steps you can take:

Clean your Air Filters, Vents, and Ducts – A clogged air filter will struggle to meet the thermostat’s set temperature since the dirt and debris buildup prevents air from circulating through the vents. And as airflow into living spaces drops, so do comfort levels. Fortunately, taking care of your filter, vents, and ductwork will help improve circulation and allow your HVAC system to meet thermostat settings effortlessly.

Start by replacing your air filters. Thoroughly wash the vents and partner with a licensed HVAC specialist to clean the ductwork. They’ll also look for leaks in the duct system that are causing heated air to escape.

Properly Size Your HVAC Unit – Did a professional HVAC contractor inspect your home before installing your new heating or cooling system? If the installation company didn’t follow the right HVAC system sizing procedure, you could be looking at an AC unit or furnace that is too big or small for your home.

Such a unit won’t deliver the same comfort levels as a properly sized one. If you find yourself in this scenario, consult a qualified professional to find out the best way forward.

Explore Other Methods When Outdoor Temperature Is Record-Breaking 

Extreme weather outside your home may make the thermostat not reach set temperature. Sometimes your HVAC system just can’t keep up with the record-shattering outdoor temps, especially if its capacity is not designed to do so. 

In this situation, deploy other methods such as closing windows and drapes, sealing any leaky areas around your home, and using a ceiling fan if it’s hot.

You Tried Everything. Now Let SuperTech Get You Comfortable!

Have An HVAC Expert Troubleshoot And Fix Your Thermostat Not Reaching Set Temperature Problems

When you lower or crank up the thermostat settings, you expect it to work its magic. When it fails you, and all the solutions fail, your best bet is to partner with SuperTech- Baltimore's top HVAC contractor

At SuperTech, we have a team of competent technicians that has the skill, experience, and resources to fix any bad thermostat or any HVAC problem you encounter. Feel free to give us a call or schedule online.

  • I have had a technician out 2x now. And still have the same problem. My vents are getting cold but you don’t feel much air coming out. I have my thermostat set on 74 and it gets up to 79 and stays that way all day. The technician says it is just hot outside. But it’s not working right.

    • Mary, if your system is having a hard time keeping up but there is nothing wrong at the system we suggest looking into your air flow. Often times, older ductwork can collapse, create leaks, and in rare times- it’s much too small for the home you’re in. If you have a local contractor you work with, ask them about an air flow upgrade. Most companies offer free estimates to help you understand your ductwork a little better.

    • Hi Bettie! Sometimes the system can be in fan mode, allowing the air to continue to circulate throughout the house when your AC or heat is not running. Do you notice if the temperature maintains what is set at the thermostat?

  • Top number is 73, larger number is 73 and it’s on cool and feels good.
    The weather outside is 80. Will my AC turn on eventually?

    • Yes! Once your home temperature goes higher than what is set on your thermostat, your air conditioner will turn on to satisfy. The opposite will happen with your heating system; if the temperature drops below your set temperature your heating system will turn on and blow hot air until it reaches the desired temperature.

    • Hi Tammy! Sometimes, you’ll need to wait a few moments for the thermostat to register the need for heat/cool. If you’re still having issue with the system turning on when your thermostat is adjusted, we highly suggest a certified technician to take a look and diagnosis the problem.

    • Hi Gloria! Do you know if your thermostat is currently on a schedule? If it’s not on a schedule and it’s having a hard time satisfying the temperature set, double check your filter (sometimes dirty filters can be a main issue), as well as the batteries in your thermostat. Have you tried any of the other troubleshooting questions we mention in this blog?

  • New electric furnace and Honeywell programmable thermostat this summer, filter changed,new batteries, tried the reset , flipped the circuit breakers on furnace n house ..inside temps reads 67 but is set at 82 to see if it comes on…NOTHING but blew cool air prior to all this?????

    • Hi there! Sorry to hear about the trouble you’re experiencing with your electric furnace and thermostat. It sounds like you’ve taken some proactive steps to troubleshoot the issue already, which is great!

      Since you’ve already checked the filter, changed the batteries, and reset the thermostat, there might be a few other things we can explore to get your system up and running efficiently. Have you ensured that all the wiring connections are secure and properly connected? Sometimes loose connections can prevent the furnace from functioning correctly.

      Additionally, it’s worth checking the settings on your programmable thermostat to confirm that the temperature is set correctly and that the heating mode is activated. Sometimes a simple adjustment in the settings can resolve the issue.

      If you’re still encountering difficulties, it might be beneficial to reach out to a professional HVAC technician for further assistance. They’ll have the expertise to diagnose any underlying issues and provide the necessary repairs or adjustments to get your system back on track.

      Feel free to reach out if you have any further questions or if there’s anything else we can assist you with. We’re here to help!

  • It’s 11 degrees outside and hv thermostat set at 74…it’s only heating up to 71. I just changed filter so it is new. Should I n put Fan…On or lv on on Auto. Is it normal in extreme low temps for it not to reach desired temps?

    • If you have a heat pump, you will notice a decrease in reaching desired temperatures at extreme lows. Heat pumps work on transfer heat and if it’s too cold outside, there’s no heat to transfer to indoors. This is where your AUX (or emergency) heat kicks on to activate an electric heater. Gas furnaces have less of an issue reaching the desired temperature due to the fossil fuel burning. Any fluctuation in home comfort can be frustrating and we always recommend calling your service provider even if it’s for peace of mind.

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