Why is my thermostat not going up?

Author: Rickey Raynor  |  Last update: Sunday, November 16, 2025

Some of the most common thermostat issues include: The thermostat is broken, not properly level, or dusty. The thermostat needs to be recalibrated. There is loose wiring causing a thermostat issue.

Why is the temperature not going up on my thermostat?

Your thermostat will not be able to reach your desired temperature if you have something blocking the vents. Check the vents around your home and make sure you do not have any items such as furniture in the way of your vent's airflow. While you're at it, make sure all of your vents are open.

Why is my AC not reaching set temperature?

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.

Why is my thermostat stuck on one temperature?

If your thermostat is battery-powered, low or dead batteries could cause malfunctions. Replace the batteries and see if that resolves the issue. Incorrect wiring or loose connections in the thermostat can lead to issues like incorrect temperature readings or an inability to adjust settings.

Why won't my AC go below 74?

Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.

My heater isn't working

Why is my AC set to 74 but reads 78?

If the temperature is set to 74°F but the thermometer shows 78°F, you will have to recalibrate the thermostat to account for this 4-degree deviation. Even with older AC units or furnaces, you might have to recalibrate your thermostat from time to time.

How long should it take to cool a house from 80 to 72?

Cooling a house from 80 to 72 degrees is a common goal for many, especially during the peak of summer. On average, this process takes roughly two and a half to three and a half hours.

How do you free up a stuck thermostat?

This is an easy problem to solve yourself by simply removing the plastic outer casing and, with a very soft brush, delicately brushing off its coil and contact surfaces. It is most effective to clean the thermostat first at its lowest setting, then again at its highest setting.

Why is my thermostat on but not cooling?

There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.

Is there a reset button on a thermostat?

Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it. For those wondering specifically how to reset air conditioner thermostat models, the process is generally the same.

How to tell if a thermostat is bad?

A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.

Why is my AC not keeping up with the setting?

One possible reason your AC is not reaching the set temperature is that the thermostat could be dirty. If dirt, dust, or other debris has accumulated within the thermostat box, it can cause the wires to heat up or other issues. Thermostats are cleaned during routine HVAC maintenance to help prevent this from happening.

Why is my house colder than the thermostat setting?

Your house and attic insulation can wear down over time. Your house also may have hidden attics that aren't properly insulated or uninsulated garage walls that are attached to your home, and this can cause problems with heat escape, unwanted airflow, and drafts. Your ductwork has problems.

How do I fix an unresponsive thermostat?

4 Steps for Troubleshooting Your Thermostat
  1. Reset the Thermostat. Like any other electronic device, sometimes a digital thermostat needs a reset to get it working properly again. ...
  2. Clean Out Dust and Corrosion. ...
  3. Test the Power and Wiring. ...
  4. Adjust the Heat Anticipator.

Why won't my house cool below 80?

Well, certain problems can prevent an air conditioner from properly cooling down your home including: A dirty air filter. A blocked condenser. A refrigerant leak.

Why is my thermostat staying at the same temperature?

A dysfunctional fan can be why your thermostat won't change temperature. This problem prevents the furnace system from forcing heated air into your home. Solution: switch off the furnace, wait two minutes, then switch off the fan.

Why wont my thermostat temperature go up?

The thermostat needs to be recalibrated.

Sometimes, your furnace or AC system won't hit the thermostat temperature because the thermostat isn't correctly calibrated. This can be a common issue with new thermostats, and also often occurs after a power outage or when the thermostat's batteries are running low.

Should I turn off AC if it's not cooling?

Yes, you should turn off your AC if it's not cooling.

Why is my AC turning on but not cooling?

One simple fix for this issue is to replace your air filters. Dirty filters can restrict airflow and cause your AC unit to work harder than it needs to. Another option is to clean your air ducts and vents, removing any debris or blockages that might be preventing the cool air from circulating properly.

How much does it cost to replace a thermostat?

Replacing a Thermostat. You'll pay between $15 and $300 for the unit in addition to labor ($65 to $100 per hour) to replace an old thermostat with a new one. However, installing a brand-new thermostat is more involved and, therefore, more expensive.

How to fix a faulty thermostat?

How to Troubleshoot and Fix a Broken Thermostat
  1. Step 1: Verify Temperature Settings. ...
  2. Step 2: Inspect the Power Supply. ...
  3. Step 3: Reset the System. ...
  4. Step 4: Clean the Thermostat. ...
  5. Step 5: Calibrate the Thermostat. ...
  6. Step 6: Test the HVAC System. ...
  7. Step 7: Upgrade to a Smart Thermostat.

How cool should my house be if its 90 outside?

If it's 90 degrees outside, most people would set their AC to a perfectly comfortable temperature of 68-72°F.

Is 72 degrees to hot to sleep in for a house?

Sleep experts believe the best temperature for great sleep is between 68-72 degrees Fahrenheit. But in addition to making you uncomfortable and interfering with healthy sleep patterns, being too hot at any time of day or night can cause health risks like dehydration and heat stroke.

Why is my AC taking so long to cool my house?

Dirt, dust mites, pet dander, debris, and other buildup can get trapped in your AC filter. Once this buildup reaches a certain point, it reduces your air conditioner's efficiency. This makes the unit work harder to cool down your home, which is why it takes longer to reach the desired temperature.

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