What can break a thermostat?

Author: Ms. Elissa Cartwright  |  Last update: Monday, August 11, 2025

Over time, the wires may become frayed or damaged, which cuts off the thermostat's communication with the system from time to time. A licensed HVAC technician can inspect the system and tell you if you have a broken thermostat or if another component is causing the problem.

What can damage a thermostat?

  • Electric shock
  • Blowing a circuit breaker
  • Damaging the thermostat unit, the electrical system or even the AC/furnace unit itself
  • Dual-fuel systems, a poorly located thermostat, whole-home humidifiers, or incorrect wiring can make the installation of a thermostat a longer, more frustrating, and more complicated process.

What would cause a thermostat to go bad?

Power problems are one of the most common causes of thermostat failure. Whether your thermostat is wired to the mains or runs on batteries, a lack of power will stop your thermostat from accepting commands and communicating with your HVAC system.

What would cause a thermostat to burn out?

This can happen if there is a power surge or if the thermostat is connected to a faulty electrical circuit.

What would make a thermostat stop working?

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.

When You Do And Do Not Need A Thermostat

How can I tell if my thermostat is broken?

7 Ways to Tell Your Thermostat Is Broken
  1. The Thermostat Has No Power. ...
  2. The AC or Furnace Won't Turn On. ...
  3. The Heater or AC Won't Turn Off. ...
  4. The Thermostat Reading Doesn't Match the Room Temperature. ...
  5. The Thermostat Doesn't Respond. ...
  6. The HVAC System Is Short Cycling. ...
  7. The Thermostat Forgets Programmed Settings.

How much does it cost to replace a thermostat?

The average cost of a new thermostat, including installation, ranges in price from $50 to $500 or more based on several factors including the type of thermostat, labor costs, the complexity of the installation, and more.

Can bad batteries affect the thermostat?

Yes, a dying battery in your thermostat can have an impact on your HVAC system. If your thermostat's battery is low, it can cause your HVAC unit to function erratically or potentially not at all. Your thermostat plays a huge role in how your HVAC unit functions as it regulates the temperature of your system.

Can a thermostat go bad without overheating?

One of the lesser-known issues is the polar opposite of overheating. Overcooling happens when the engine does not reach the right temperature for its normal function. In this scenario, the thermostat is stuck open and overflows the radiator with coolant, drastically reducing the engine life cycle.

Why did my thermostat go out?

The most common reasons for a blank thermostat screen are dead batteries, a power outage, a tripped circuit breaker, faulty wiring, or a failed thermostat. The screen will be completely dark and unresponsive when there is an issue with power reaching the thermostat.

What is the lifespan of a thermostat?

The Lifespan of a Thermostat

On average, most thermostats last about 10 years, depending on the model, usage, and proper maintenance. However, many people decide to replace their unit sooner to take advantage of new energy-saving technologies.

Can a bad thermostat cause a blown head gasket?

Blown head gaskets can happen when an engine severely overheats due to a faulty thermostat, clogged radiator, leaking water pump, radiator, radiator hose or heater hoses or when the coolant in the cooling system is not changed per the O.E.M.'s scheduled maintenance.

How to unstick a 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.

What goes bad in a thermostat?

Wiring can shift and come loose over time. When the wiring between the thermostat and the air conditioner, furnace, or heat pump comes loose, it will break the connection and leave you cold. Wiring defects can also cause the system to misread temperature settings.

Can a broken thermostat cause a fire?

Additionally, a faulty thermostat can cause your heater to overheat, which can be a fire hazard.

What to do if your thermostat breaks?

To fix a broken thermostat, you should check and adjust the settings, replace the batteries, clean the thermostat, check the wire connections, and reset the circuit breaker.

Can I drive with a broken thermostat?

If you drive with a bad thermostat, your car could overheat, causing severe and expensive engine damage. And while it's technically possible to drive without a thermostat, we don't recommend it. Your car will not reach an acceptable operating temperature, resulting in higher fuel consumption and excessive engine wear.

How much is a new thermostat for a car?

Car thermostat replacement time is 30 to 60 minutes, depending on the make of the car. It will cost you around $190 to $350, including labor. Thermostat repairs usually take more time, requiring extra time to diagnose and analyze the vehicle's thermostat. It can take up to 2 hours.

How does a car act when the thermostat is bad?

You Notice Erratic Temperature Changes

If you notice sudden and erratic temperature changes from cold to hot or hot to cold, then it could be a sign that your thermostat has stopped working correctly. Get your vehicle inspected if you notice these extreme temperature changes in your vehicle interior.

What causes thermostat damage?

Over time, dust, dirt, and lint can find their way into the thermostat housing and block the sensors. To fix this problem, remove the cover and clean the parts inside using a soft-bristled brush.

Will AC still work if thermostat is out of battery?

Dim Display: A dim or faintly lit display is often a telltale sign that the battery is running low and needs replacement. HVAC System Malfunction: A failing thermostat battery can cause your heating, ventilation, and air conditioning (HVAC) system to operate erratically or not function at all.

How can I test if my thermostat is bad?

6 Signs Your Thermostat Is Broken
  1. Your HVAC System Won't Turn on. ...
  2. Your Air Conditioner or Heater Runs Non-Stop. ...
  3. Differing Temperature Readings Throughout the Home. ...
  4. Short-Cycling. ...
  5. Programmed Settings Keep Getting Deleted. ...
  6. There's No Response to Changes in Temperature Settings.

Can I replace my thermostat myself?

In most cases, installing a new thermostat is a relatively simple do-it-yourself project that can result in improved comfort and convenience and one that can help you save energy.

Who fixes a broken thermostat?

There are multiple factors at play when you have a thermostat issue. Only an HVAC professional can diagnose the root of AC repair problems and offer technical solutions for them.

How many hours does it take to replace a thermostat?

Installation typically takes about 1 hour.

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