HVAC Repair Tips


Sometimes, the cause of your HVAC problems is not the mechanical components of the air conditioner, but any other part. This is why getting help from an HVAC repair service is important so the issue is detected early on and fixed properly. If your air conditioner thermostat is failing, it will directly impact the functionality of your AC. So, identify and fix thermostat problems with this guide.

Signs Of A Failing Thermostat

Use these signs as a hint because the issue could be something else. For instance, if the AC is short cycling, it can be due to a faulty thermostat, but it can be because of other things as well like an oversized HVAC system.

Unresponsive Thermostat

A clear sign of a thermostat problem is a thermostat that doesn’t respond to anything. You will see a blank screen and it won’t trigger a response if you press any buttons.

The HVAC Unit Won’t Start

Even when your HVAC system is sound, it won’t turn on if the thermostat malfunctions. The electrical wiring that signals the air conditioner to start or stop functioning may have failed. So, your AC won’t turn on and you will wonder if your air conditioner is broken.

Your HVAC Won’t Turn Off

Similar to the reason a faulty thermostat can prevent an AC from turning on, it can also stop malfunction during the functioning of the AC. So, when the AC should turn off automatically, it won’t because of the thermostat failure.

Incorrect Thermostat Readings

As we all know a thermostat shows the current temperature of the room/house on the screen. It helps you adjust the temperature as required. But when a thermostat is faulty, it won’t show the correct reading. A hint to this is you would feel your house warmer or cooler than the temperature displayed on the thermostat.

This problem will also give way to the issue of your AC not heating or cooling the house as required because it can’t detect the temperature correctly.

To be sure, you can also use an indoor thermometer and match the reading of the thermometer with your thermostat.

Thermostat Forgets Settings

Programmable thermostats are made to keep the settings you store for different times of the day and different days of the week. However, when a thermostat becomes faulty, it might start to forget programmed settings.

This means it might not turn off the AC as you programmed or won’t turn on the AC at the time you set it to.

Even if you program the thermostat again without fixing the problem, it will forget the new settings as well.

Short Cycling

Short cycling is an AC turning off before completing its heating or cooling cycle. Due to this, your air conditioner won’t cool the house properly. Moreover, constant turning on and off of the AC would use more electricity and it will also wear the AC components more quickly.

Fixing Thermostat Issues

Check The Batteries

Over time, corrosion on the batteries can restrict them from powering the thermostat. The thermostat might function abruptly. So, remove the batteries, clean them yourself, or have a professional look at them and clean them.

Replace The Batteries

An easy fix for many thermostat problems is the replacement of batteries. Your battery-powered thermostat may be not responding, displaying a blank screen, or forgetting programmed settings due to drained batteries.

Programmable thermostats show a warning signal when the batteries are depleted. In any case, if your thermostat’s screen is blank and it’s totally unresponsive, it may be due to drained batteries.

So, open the battery compartment of the thermostat, notice the type of batteries required for it, buy them, and replace the old batteries.

Keep in mind that thermostat batteries usually last for a year so replace them annually to avoid going through the whole thermostat troubleshooting process.

A Circuit Breaker Issue

What if when your AC doesn’t turn on or your thermostat doesn’t respond, both are completely fine and the problem is something else? It can happen if your circuit breaker trips. With this, your AC and thermostat will not receive power to turn on, so they won’t respond.

A circuit breaker trips due to a power surge, electrical overload on the circuit, or an issue with any of the appliances that are receiving power from the circuit breaker.

However, if there are no signs of burning, no smell, noise, or sparks from the circuit breaker or the breaker box, you should turn on the circuit breaker. But if it trips again in a short time, refrain from turning it on again and consult an electrician because there could be a problem, and ignoring that can lead to a fire.

Clean The Thermostat

Many wouldn’t believe that a cause of thermostat issues can be dirt and debris buildup on the device, but it’s a common reason for thermostat malfunctions and is also easy to solve.

What happens is that dust and dirt build up inside your thermostat and block it enough for it to show inaccurate readings. Once the thermostat incorrectly detects the temperature, it can’t cool or heat the house as required because even if reaches the set temperature, it would actually turn off on a temperature higher or lower than the actual temperature due to incorrect temperature detection.

For cleaning the thermostat, remove the upper cover of the device. Set the thermostat to the lowest settings. Use a small soft-bristled brush or a microfiber cloth. Wrap the cloth on your finger and gently clean the interior.

Then, set the thermostat to the highest temperature setting, and clean the bimetallic coils again. After completing this process, you can set the temperature as you like. Moreover, use a room thermometer to check if the thermostat is back to normal functioning.

Programming Defects

Programming glitches in the thermostat can also lead to issues including AC not cooling enough, short cycling, and others. Typically, it happens due to a sudden power failure or power fluctuations and affects the functioning of the chip inside thermostats.

Programming defects can only be fixed by reprogramming the thermostat. This means you will have to set your preferences again on the thermostat.

Faulty Wiring

A thermostat with loose connections, disconnected wires, or faulty wires will obviously show problems. Check the internals of the thermostat by removing its cover to inspect the wiring. If there are any wires plucked out, place them back if you know where they belong. You can also fasten wires that may appear loose.

However, if the thermostat doesn’t work after this fix, the thermostat needs a meeting with an AC expert.

Old Thermostat

Your thermostat may be faulty because it reached the end of its lifespan. With time, your thermostat may show problems like wiring issues, wear and tear, and rusting. When these issues become prominent enough to impact the functioning of the thermostat or stop it from working, the thermostat has aged.

A typical HVAC thermostat lasts for 10 years. So, if yours is near that, consider a replacement.


A faulty thermostat can render your entire HVAC system inoperable. So, detect the problems and fix them with the above-mentioned tips. Get help from authorized air conditioner repair services Fairfax if required.


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