Furnace Won’t Reach Set Temperature – What To Do?

Furniture issues can be extremely frustrating, especially when they occur during the coldest months of the year. One common problem that you may face at some point is when your furnace fails to reach the temperature that you set for it. How do you fix this issue? And what causes it? We've looked into possible reasons for this. In this post, we will go over them.

Here are reasons why your furniture may not reach its set temperature:

  • A breaker has tripped
  • Furnace sensor issues
  • Furnace is overheating
  • Blocked furnace airflow
  • A clogged air filter
  • Blower or belt issues
  • Furnace thermostat problems
  • Electrical wiring issues

man fixing the home furnace thermostat. Furnace Won't Reach Set Temperature - What To Do

Reasons Why Your Furnace Won't Reach Set Temperature

electronic climate control device all white. Furnace Won't Reach Set Temperature - What To Do

A Breaker Has Tripped

Sometimes the breaker in your home or apartment building may trip, causing the heat to turn off. Take a look at the breaker and make sure that it has not tripped. You can do this by opening up the breaker box and flipping the switch on and off. If the breaker has been overloaded, it may need to be reset, or you may need to have an electrician come and take a look at it.

Furnace Sensor Issues

Your furnace could also be experiencing a malfunctioning flame sensor. The flame sensor is responsible for igniting the fire inside the furnace. In which case, the sensor may need to be cleaned or replaced with a new one. This part typically costs around $30 to $50. It's best to have a repair technician install it, as you'll need to open up the furnace and remove the wiring from the old filter.

Furnace Is Overheating

Most modern furnaces have a safety mechanism installed in them that will shut off the furnace if it gets too hot. This mechanism prevents the furnace from overheating. A furnace can start to overheat for a myriad of reasons.

If you noticed that your furnace is getting too hot, it might result from loose parts within the furnace or a broken component. Sometimes overheating can be challenging to troubleshoot. In which case, the consultation of a qualified HVAC professional can be very useful. They can assess your furnace and tell you what the underlying issue is.

Blocked Furnace Airflow

Blocked airflow is another reason why a furnace may not reach its desired temperature. If the airflow inside the furnace cannot blow freely through the vents, the hot air cannot reach the areas of your home to warm it up. The best way to determine if this is the issue is by checking the furnace and then inspecting your vent ducts.

Make sure that the ducts are open and free of obstructions. Also, make sure that the furnace itself is blowing hot air through the vents. You should be able to feel warm heat radiating from the furnace if you stand near it. If you don't, there could be an underlying issue with the furnace itself.

A Clogged Air Filter

A clogged air filter is probably the most common reason why a furnace will not reach the desired temperature. Not only can clogged air filters block heat from reaching the vents, but they can also cause the furnace to overheat, as it overworks to try to push the air through the vents and the filter. It's best to change your air filter every month, especially if you live in an area with many trees or polluted air.

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Blower or Belt Issues

If your furnace is experiencing blower issues or problems with the blower belt, it can affect its ability to supply warm air to your home. The blower itself is responsible for circulating air from the furnace to the vents. The belt allows the blower to spin. If the belt is broken, the blower cannot turn effectively. You may hear strange sounds coming from your furnace if this is the issue.

These issues are best left to a qualified HVAC specialist, as they can involve opening up the furnace and removing parts that are difficult to reach. Replacing a furnace blower can be rather expensive, so it's best to take a look at your furnace as a whole and determine if the entire system should be replaced or just the blower itself.

Electrical Wiring Issues

Sometimes frayed, old, and loose electrical wires can cause the thermostat to lose its connection to your furnace and heating system. When this happens, you may experience the furnace's not heating, heating at incorrect temperatures, or blowing out cold air. You can look at your fuse box to determine if there are fuses that have tripped or blown out.

Also, look for any loose wires or other obvious electrical issues. If it's merely a fuse, you can use a multimeter to test its continuity. And if it's blown, you can replace it. If the fuses and wires appear fine, an electrician can help determine how to continue troubleshooting the issue.

Click here to see this multimeter on Amazon.

Why is my thermostat not reading the correct temperature?

One of the most common reasons why a thermostat may not read the correct temperature is that it has a malfunctioning sensor. If the sensor has failed, it may need to be cleaned or replaced altogether. Sometimes sensors can become cloudy with dust, which can cause them to malfunction and display incorrect temperatures. Try cleaning off the sensor first, and if this doesn't work, check your user's manual for troubleshooting tips.

Why can't I change the temperature on my thermostat?

If you cannot change the temperature on your thermostat, there are a few reasons why. Let's look at the most common ones.

It's In Auto Mode

Most modern thermostats have an auto mode setting that allows you to create temperature settings for specific days or specific times of the day. These pre-programmed temperatures are typically available when the mode is set on " Auto." To manually override them, you will need to switch the mode of the thermostat.

It's Reached A Set Temperature Limit

Most thermostats can be pre-programmed with a low and high limit. These limits allow the thermostat to hold a specific temperature without changing it--a setting that can help to reduce your heating and cooling costs. Typically, these settings won't allow the thermostat to heat the home over 85 degrees Fahrenheit or cool it below 55 degrees.

If you find that your thermostat has reached the set temperature limit, you can contact an HVAC service provider about resetting the limit--though this is not typically recommended. A better option would be to install a portable heater.

The Thermostat Needs Cleaning

A dirty thermostat can begin to malfunction over time, which can cause it to lock up when you try to change any of the settings. Try turning the thermostat off, resetting it, and then cleaning it off with a microfiber cloth to remove any dust or grime that may have accumulated on it.

The Thermostat Needs to Be Reset

If the thermostat needs to be reset, it may become inoperable at some point. If you don't see a reset button on your thermostat, look at your user's manual to locate it. Something thermostats have a tiny reset hole that will only be accessible with a paperclip or a pen's end.

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What temperature heat should come out of vents?

The air coming out should be 14 to 20 degrees cooler than the air flowing in. To test the air temperature coming out of the vents, take a thermometer and place it next to each pint of your home. Note the temperature and compared it to the temperature on your thermostat. If the difference is greater than 20 degrees, it could be a sign that your furnace or thermostat is experiencing issues.

Why is my furnace blowing cold air while the heat is on?

If your furnace is blowing cold air while you have it on a heat setting, there can be a few reasons for this. Here are the most common ones.

Leaking Ducts

Ductwork is responsible for carrying heat throughout your home. If you have holes or gaps in the ductwork, warm air will escape and will not reach its desired location, resulting in cold air blowing from the vents. When troubleshooting a potential ductwork issue, be sure to first check the ductwork for signs of leakage or damage.

Faulty Flame Sensor

A faulty flame sensor can also be a common reason why your furnace may blow cold air. The flame sensor is responsible for igniting the fire of the furnace. Over time, these sensors can become worn, which will cause the burner to shut off. An HVAC technician can replace the sensor for you or clean it if necessary.

A Bad Thermocouple

Sometimes thermocouples will begin to malfunction, which may cause the furnace to blow out cold air. These sensors control the gas valve and the ignition of the furnace. They can be replaced relatively easily, and you can even perform this repair yourself.

A Dirty Filter

A dirty air filter can also block air movement throughout your furnace. This blockage can cause the temperatures inside the furnace to rise, and as a result, the limit switch will shut down all of the heating cycles. When this happens, you may notice that the furnace is now blowing cold air. Take a look at your air filter, and if it is dirty, change it out. Ensure that the new filter is the same dimensions as the old filter and always follows the directional markings to ensure proper positioning.

Wrapping Things Up

We hope that this post has provided you with the information you were looking for to troubleshoot a furnace when it is not. But before you go, be sure to check out some of our other posts:

How To Place Living Room Furniture

Can You Cover A Vent With Furniture?

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