why is my ac thermostat not working

by Kaylin Stiedemann Published 2 years ago Updated 2 years ago

A few things may go wrong that cause a thermostat to turn unresponsive:

Loss of direct connection to the air handler or compressor. ...
The thermostat has become miscalibrated, which means it’s reading incorrect temperature settings in the house. ...
The software in the thermostat has malfunctioned. ...
The thermostat is mismatched with the HVAC system. ...

If your thermostat is not working, change the batteries, make sure it is turned on, the thermostat is set to the correct mode, check the power supply and airflow. If your thermostat is still not working, the best thing to do is call an HVAC professional! They will be able to help you diagnose and repair the issue.

Full Answer

How to fix AC thermostat?

2 Remove Existing Thermostat. Remove the old thermostat cover plate with a screwdriver. ...
3 Separate & Label Wires. ...
4 Install a C-Wire if Needed. ...
5 Install the New Thermostat Base and Wire. ...
6 Mount Thermostat and Restore Power. ...
8 Tips for Installing Programmable Thermostats. ...

What would cause a thermostat to stop working?

You can also try these five hacks to make it happen faster:

Replace the batteries inside your thermostat. They could have been zapped.
Reconnect the system to your smart devices. Uninstall and reinstall the app.
Clear the way for a good connection. Clean debris from your circuit breaker and fuses.
Stiffen up. Look for loose screws in the electrical terminal and tighten the ones you find.
Get an upgrade. ...

How to check air conditioning when AC not working?

Method 3 of 3: Diagnosing Air Temperature Problems

Find the front of your AC condenser. It is normally located in front of your radiator. ...
Look under the hood at the AC compressor clutch. If your air pressure is normal but the air is hot, you may have a compressor problem.
Check the tension on the belt of the compressor. It should be tight. ...
Find any coolant system leaks. ...
Check for freezing. ...

Why is my home thermostat not working?

Why is my thermostat is not working? There are so many reasons if your thermostat is not working, like Dead Battery, Blown Fuse, Loose Wiring, a faulty thermostat, and Faulty Heat Anticipator, etc. Some errors can fix at home, or some defects can only repair by experts.

Why is my thermostat off?

How to tell if thermostat is not working?

How to fix a thermostat that is blown?

Why is my thermostat messed up?

Why is my thermostat not sensing the temperature?

Why does my AC keep clogging up?

How should a thermostat be installed?

See 2 more

What causes a thermostat to stop working?

Loose connections, frayed wires, and aged wires all can cause your thermostat to eventually lose its connection to your A/C and heating system. Inspect your wiring thoroughly, making sure the connections are tight, and replace any wires as deemed necessary by you or an HVAC professional.

How do I reset the thermostat on my AC?

Common methods for resetting a thermostat include installing the battery backward for five seconds, pushing a recessed reset button with a pin or paper clip, or shutting off the breaker to the thermostat for 30 seconds.

Why is my air conditioner not responding to my thermostat?

The thermostat may only appear to have failed. The problem may be elsewhere in the HVAC system. The air conditioner's limit switch has tripped. If the condensate pan in the air conditioner overflows because of a clogged drain or a broken pump, it will automatically shut down the air conditioner.

What is a common problem with thermostat?

A common thermostat issue that usually results in the temperature never reaching what you have it set for. Grime can build up inside a thermostat. When this happens, the thermostat doesn't correctly gauge the temperature of the air in your house. Older thermostats can be cleaned by dusting inside the cover.

Where is AC reset button?

Look for it first around on the exterior of your machine, especially along the bottom edge near the ground. An AC's reset button is typically red and visible, so it should be easy to spot. If you don't see a reset button on the outside, it could be located inside the unit behind the service panel.

How do I fix my thermostat?

0:141:35How to Troubleshoot a Thermostat | The Home Depot - YouTubeYouTubeStart of suggested clipEnd of suggested clipThen reattach it to the terminal. Once you have repaired any wiring. Issues place the cover back onMoreThen reattach it to the terminal. Once you have repaired any wiring. Issues place the cover back on the unit.

How do you tell if you need a new thermostat in your house?

Signs You Need a New ThermostatHeating or cooling system will not turn off or on.The temperature reading is incorrect.Recent spike in your energy bill.Frequent temperature fluctuations.Thermostat is 10 years old or older.

How do I test my home thermostat?

0:494:49How to tell if your home thermostat is bad - YouTubeYouTubeStart of suggested clipEnd of suggested clipWith this setting your fan should start blowing regular home air non-stop regardless of theMoreWith this setting your fan should start blowing regular home air non-stop regardless of the temperature settings you have on your thermostat. Whether. It's for cooling or heating.

How much is a new thermostat?

Written by HomeAdvisor. The average thermostat replacement cost runs $175, or between $113 and $254. The cost to install thermostats runs slightly higher since it may require running wires and determining placement. Thermostat prices range from $15 to $500 or more, depending on the type and features.

When should I replace my AC thermostat?

7 Signs You Need to Replace Your ThermostatYour HVAC Keeps Turning On or Off. ... Faulty Thermostat Readings. ... Suspiciously High Energy Bills. ... Constant Temperature Shifts. ... Thermostat Is Too Old. ... Thermostat Fails to Respond to Changed Settings. ... Your HVAC System Short Cycles.

How do you know if your thermostat is fried?

Signs of a Bad ThermostatYour thermostat has no power or is unresponsive. ... Your A/C or heater runs constantly and won't turn OFF. ... Room temperature and setting don't match.

How do you reprogram a thermostat?

0:342:05How To - Program a Programmable Thermostat - YouTubeYouTubeStart of suggested clipEnd of suggested clipWe'll want to raise the temperature again before they get home. This will keep them warm in theMoreWe'll want to raise the temperature again before they get home. This will keep them warm in the evening. Before the temperature drops again at bedtime.

How do I reset my digital thermostat?

A common way to reset almost any thermostat is to hold down the reset button for 5+ seconds. Alternatively, try resetting battery-powered thermostats by flipping the battery directions around for 5s, then flip them back. If all else fails, switch off the power at the circuit breaker for a couple minutes.

How do I calibrate my thermostat temperature?

To do so, locate your home's thermostat and tape an accurate thermometer on the wall next to it. Wait 15 minutes and check the temperature reading on both devices. If your readings are three or fewer degrees apart, you should be good to go.

Is there a reset button on outside AC unit?

But if you're wondering where is the reset button or switch on the air conditioner unit, look for a small and red button or switch on the air conditioner. If you don't find any reset button, your AC probably doesn't have one, and to reset your air conditioner, you'll have to do it manually.

4 Reasons Why Your Thermostat Isn’t Working

Do you ever look at your thermostat and feel your home’s temperature and know something isn’t adding up? Between what you are reading on your thermostat and what heat is being produced by your HVAC system (and not being produced, of course) lays many possible issues and solutions.

5 Reasons Your Thermostat Isn’t Working - The Spruce

The Thermostat's Connections Are Loose . Your thermostat relies on a few essential electrical connections to get the job done. When a thermostat senses a problem, each individual connection allows it to send power to the necessary component for the solution.

Why is My Thermostat Not Working? How to Fix [With Pictures]

If your thermostat is not working, you may want to check the airflow. Airflow is a significant factor in how your heating and cooling system performs. The airflow is responsible for supplying cool air to the rooms in your home. If the airflow is blocked, your HVAC system will struggle to satisfy the thermostat, and the thermostat will not function properly.

The Thermostat's Power Source Is Failing

You head over to your thermostat and notice the screen is dark. More than likely, this means there's no power getting to it. First, ensure the power switch is fully engaged. If so, remove the cover and replace the battery. If this doesn't do the trick, look for a blown fuse or tripped breaker.

The Thermostat's Connections Are Loose

Your thermostat relies on a few essential electrical connections to get the job done. When a thermostat senses a problem, each individual connection allows it to send power to the necessary component for the solution. Most basic thermostats include a heating connection, cooling connection, and fan connection.

The Thermostat Is Dirty

Thermostats, like many other electrical appliances, will malfunction if they're allowed to get too dirty. Dirt, dust, and debris can pose problems for both electrical and mechanical components, causing your thermostat to fail. Turn off the power source and remove the thermostat's cover.

The Thermostat Isn't Level

Does your thermostat's temperature readout not match the room's actual temperature? This could be because the thermostat itself isn't level on the wall. Thermostats that feature a mercury bulb must be level to operate. To fix this, turn off the power supply and unmount the thermostat. Use a level to ensure it's perfectly level when remounting.

The Thermostat Is Installed in the Wrong Spot

Maybe your thermostat is properly communicating with your HVAC system, it just never seems to keep up with your home's needs. A thermostat installed in an improper place in your home can sense an inaccurate picture of your home's environmental needs.

When to Replace Your Thermostat

There are two main reasons you would need a different thermostat. First, your thermostat could simply be in need of replacement because of age. Like most components of a home, thermostats eventually get old and go bad.

When to Call a Professional

If you've tried these simple troubleshooting tips to no avail, it may be time to call in a professional. From electrical knowledge to in-depth knowledge of different HVAC systems, an experienced HVAC technician will have all the tools and know-how needed to get your thermostat up and running without a hitch, no matter the problem.

Why is my thermostat off?

It might be possible that your thermostat is just set to the “off” position, which is easy to fix by switching it back on. If this does not work, you can also try resetting the thermostat. Another possibility is that something might be wrong with the power supply. There could be an issue with the batteries inside the unit or with your house’s electrical system.

How to tell if thermostat is not working?

If you are noticing heating or cooling issues , this might mean that your thermostat is not working. One sign that might point to an issue with your thermostat is if your air conditioning unit is not reaching the set temperature. Similarly, if the unit keeps shutting off early or it is running all the time, then your thermostat might be the problem. Another common sign is if the display on the thermostat is blank.

How to fix a thermostat that is blown?

If you find that a breaker has tripped, then flip the circuit breaker for the thermostat back to the on position . Lastly, if your thermostat has batteries inside it, then you can replace the batteries to see if this fixes the problem.

Why is my thermostat messed up?

The calibration on your thermostat can get messed up if the thermostat is new or if you have had a power outage recently. If this is the issue, then recalibrating the thermostat should fix the problem. However, if this does not correct the issue or if you find yourself having to recalibrate the thermostat several times each year, then your thermostat might have gone bad or have another problem.

Why is my thermostat not sensing the temperature?

If your thermostat was installed crooked or in a bad spot, this can cause it to have trouble sensing the true temperature of the house. For example, if your thermostat is in the kitchen, this can cause it to think the whole house is warm. In reality, it might be just the room where the thermostat is located that is hot, while the rest of the house might be freezing cold.

Why does my AC keep clogging up?

If your air filter is clogged or the vents or ducts are dusty or dirty, this can block air from flowing through your HVAC system. This can keep the thermostat from reaching the set temperature. You can prevent this problem by signing up for regular AC maintenance.

How should a thermostat be installed?

When a thermostat is first installed, it should be level and should be placed flush against the wall. Otherwise, this can affect the thermostat’s ability to read the temperature of the room. Similarly, the internal parts of your thermostat can break down, loosen or gather dust over time. This can also keep the unit from working like it should.

What happens if your thermostat is not working?

If the wiring is not properly connected, loose, or corroded, the thermostat will not function to its fullest capacity. After tightening wires that appeared loose or replacing any corroded wires, check to see if you can turn on your AC.

Why won't my thermostat communicate with my air conditioner?

In many cases, thermostats won’t properly communicate with their air conditioning systems because of a simple error in the thermostat settings.

How to tell if thermostat is in a poor location?

A good indicator that your thermostat sensors have been placed in a poor location is if the temperature on your thermostat appears much higher or lower than it feels in your home. (You can also purchase a hygrometer to place in your home, which reads the temperature and humidity of your home; they cost around $10).

Why does my AC kick on?

When your thermostat reaches a temperature higher than it is set for, your AC should kick on. If it still fails to turn on, this is not the issue. 6. The thermostat itself has defects. Last but not least, it’s possible that your thermostat itself has defects that are out of your control.

How to make AC not kick on?

First, make sure that your thermostat is set to “cool” and not “heat.”. If your settings aren’t on “cool,” your AC won’t kick on. If that looks good, the next thing to consider is if your fan is set to “ON.”. Instead, it should be set to “AUTO.”. If that doesn’t do the trick, you might consider trying to set your thermostat five degrees higher ...

Is there power for a thermostat?

There’s no or little power for the thermostat. Sometimes, installation isn’t necessarily the issue. Another significant aspect of ensuring that your thermostat is able to adequately communicate with your air conditioner is checking the power supply.

What is wrong with my thermostat?

Another major problem with a faulty thermostat is the temperature control. If you are finding that the AC unit is making the room too cold, despite having programmed the thermostat to a suitable level, you need to check that the thermostat is working correctly.

How to fix a thermostat that is not working?

Check that there is no dust and debris on any other part of the thermostat, and then reinstall. Turn the power back on, and program your AC thermostat for your ordinary cooling requirements, then wait to see whether your troubleshooting has worked.

How to clean a thermostat?

First, ensure the power is turned off, and then remove the cover of your thermostat. Locate the bimetal coil inside, and brush it free of dust using a soft brush, such as a shoe polish brush. Unscrew the body of the thermostat, and brush off the top and the mounting plate. Use a piece of cleaning paper, known as bond paper, to remove any dirt between the contacts.

How to check if thermostat is faulty?

Firstly, ensure that there is power to the thermostat, both by checking the wiring supply to it, and also by replacing the batteries. Try turning the power on again. If nothing happens, turn power off and proceed. The next thing to do is to check that the thermostat is clean, and that it is not faulty.

What is the ampere setting on an AC unit?

An AC unit will require the ampere setting found at the last stage of the manual's instructions. Another problem may be that the thermostat is not level, causing the temperature gauge inside to be misaligned. Use a level to check the alignment, and adjust it if it is out of sync.

Why does my AC stop working?

Short cycling is when your air conditioner turns on and off again in very short bursts without completing a full cooling cycle. When filters are blocked your AC unit has to work harder, creating higher energy bills and unevenly cooling your home. It may even cause your air conditioning system to stop working.

Why Is My Air Conditioner Not Turning On?

If your air conditioning system just isn’t turning on then we suggest you run through a few things before calling in an HVAC expert:

Why Is My Air Conditioning Fan Not Working?

If your air conditioning fan isn’t working your HVAC system won’t cool your home.

Why Is My Air Conditioner is Making Noise?

Rattling or banging could mean something has come loose, while buzzing often means you have an electrical issue. Any kind of persistent noise is a cry for help from your air conditioning unit. Turn off your AC and call an HVAC professional to come out and assess your system for issues.

What does it mean when your AC makes a rattling noise?

How do I troubleshoot an air conditioner?

No matter what type of system you have – central, mini-split, ductless, or heat pump – there are commonalities between the types of AC systems that our troubleshooting guide covers. If your air conditioning system just isn’t turning on then we suggest you run through a few things before calling in an HVAC expert: 1 Make sure the outdoor breaker fuse is positioned correctly 2 Check your electrical panel for a tripped breaker 3 Confirm that your thermostat is switched on 4 Check for a clogged air filter 5 Check your condensate pump for proper operation

How to fix a clogged AC?

Make sure the outdoor breaker fuse is positioned correctly. Check your electrical panel for a tripped breaker. Confirm that your thermostat is switched on. Check for a clogged air filter. Check your condensate pump for proper operation. If you check these and all is in order then read on for other solutions to AC problems.

Why does my thermostat not match my temperature?

The temperature doesn’t match the thermostat reading: If the conditions you feel in your home do not match the temperature reading on the thermostat, your unit may be damaged . Use an external thermometer to take a second temperature measurement and compare it to the information on your thermostat.

Why won't my AC turn off?

Your AC won’t turn off or on: If your air conditioning system seems to be stuck in a continuous loop — either constantly running or unable to turn on — it may be a problem with your thermostat’s position or internal trigger. Unlevel units or damaged wiring can make it impossible to stop or start your unit.

How to reset a thermostat?

Hold the reset button: If your thermostat has a manual reset button, press and hold it for several seconds or until you see or hear the unit restart. Turn it on and off: Turn your air conditioner and thermostat off and allow them to rest for several minutes before turning them back on.

How to improve thermostat reading?

Large obstructions, like furniture, can also interrupt thermostat readings. Always install thermostats in an area that is easy to access and near the room’s natural air currents.

How to check if a thermostat is tripped?

To check for a tripped breaker, look at the panel and see if the switch next to your HVAC system is hovering between the “off” and “on” position or if a light indicates a trip. Reset the switch if necessary.

What is a manual thermostat?

Manual: Manual thermostats use a series of wires, switches and a thermometer coil to move currents either left or right to trigger hot or cold air from your HVAC system. Programmable: Programmable thermostats are a specific type of electronic or digital thermostat that lets you establish operation parameters.

Why does my thermostat fluctuate?

The temperature fluctuates from room to room: If your home’s temperature feels different in separate rooms or corners — despite a set temperature on the thermostat — it could indicate a damaged unit.

Why is my thermostat not receiving power?

It’s always possible that there is an underlying wiring issue preventing your thermostat from receiving power . If you suspect this might be the case, we recommend calling an HVAC professional for this one.

Why does my thermostat shut off?

This can cause the circuit breaker to trip, which will shut your thermostat off.

What is a safety switch on a thermostat?

Certain thermostats are equipped with a safety switch, which is triggered whenever a potential threat to your air conditioning system is detected. Let’s say your evaporator coils freeze and cause excess condensation to drain from your system – in a case like this, the safety switch may alert your system to shut down, causing your thermostat to turn off.

What is the thermostat in an air conditioner?

The thermostat is one of the most important components of your air conditioning system. Without it, you wouldn’t be able to turn your AC on and off or take advantage of the cooling and heating benefits your system offers you.

How long does a thermostat battery last?

This is another ‘silly’ thing that can cause your thermostat to go blank. The batteries in your thermostat can last as long as five years or as little as a few months – so if your thermostat is turned on but still blank, try swapping out the batteries.

Why does my AC shut down?

Over time, the air filter in your AC system gets bogged down with dirt, dust, and other debris. If it becomes too clogged, it can impede airflow and cause your system to shut down. Take a look at your air filter. If it’s dirty, replace it with a new one.

Can you replace an air conditioner part?

Unfortunately, replacing a single part here and there can affect your entire system if the part isn’t compatible.