Why Air Conditioner Heat Mode Not Working? - HVAC BOSS (2024)

Having the option to use the same air conditioner unit for heating and cooling is one of the 21st century’s most underappreciated luxuries. However, what happens when you’re left without that option?

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An air conditioner’s heat mode may not be working because it’s not on the correct settings or there’s no heat mode function. It could also be due to dirty filters, circuit breaker issues, obstructed airflow, or the unit going into defrost cycle. Luckily, these issues are easy to solve.

To put your mind at ease, I’m dedicating this article to explaining the potential issues one might run into with their air conditioner’s heat mode. I’ll also be sharing some simple tips and tricks on solving, or potentially even preventing, these problems.

What Is the Heating Mode in AC?

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Whether the air is coming from the ducts, a wall unit, or an AC device installed on a window, air conditioners with a heating mode are something everyone on the market for a new AC should consider.

There are many benefits to installing an air conditioner that can heat your home and cool it. On the other hand, there are a few drawbacks to these home appliances.

Here’s a short list of the pros and cons of buying an AC unit that is capable of heating:

AC with Heat Mode
Offers heating optionCost more to buy than a regular AC unit
Decreased power use compared to traditional AC unitsCosts more to maintain and repair compared to conventional AC units
More effective coolingMore frequent service intervals

Read: Why Does Air Conditioner Run At The Same Time As A Furnace?

Reasons AC Heat Mode Isn’t Working (and How To Fix It?)

There’s nothing worse than sitting in a cold room, staring at an air conditioner that can’t do its job and get you warm.

Before jumping into exploring the reasons behind the AC heating problem, I should note that every unit needs a few minutes to warm up before it starts to produce heat. Make sure you’re giving it enough time before panicking.

While there might be other reasons why your AC unit can’t produce heat, the most common ones are:

The Unit Has No Heating Option

There’s one solution to our problem of the day that seems basic but is commonly overlooked.

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Readers who have just bought a new air conditioner and are experiencing problems with the heat mode might need to check out the user manual:

Ensuring that your unit is equipped with a reversible air conditioning system should be the first thing you look at when the machine won’t start heating. AC buyers are commonly under the misconception that all of the units are the same.

Prevent buying a non-heating AC unit by talking to the seller or checking the model’s specification list online.

If you can’t find the info in the manual, having the heating mode icon displayed on the remote controller should clearly indicate whether you can use the AC for heating.

You’re Using the Wrong Settings

Turning the air conditioner on just like you do during the summer isn’t going to cut it. For the heating mode to work, the settings need to be adequately adjusted.

Here’s how you can make sure that your AC unit is in heating mode:

  • Set the mode to HEAT: Avoid putting the unit in Auto mode if you want to heat up the space.
  • Set the temperature higher than for cooling: For the heating function to work right, your air conditioner’s temperature needs to be set higher than usual. While the government-recommended setting for heating of 68°F (20°C) is excellent for saving on electricity, it won’t be enough to start the heat pump. Set the temperature to 75°F (24°C) or higher instead.
  • Adjust the fan speed: Once again, you don’t want to leave the AC unit in auto mode. Adjust the fan direction and speed according to your preference instead.

Если в настройках нет причины, по которой кондиционер не может начать нагрев, перейдите к следующему элементу в списке.

Read: Why Does The Room Temperature Not Match The Thermostat Setting?

The Air Flow to the Unit Is Restricted

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After adjusting the settings, the next step in solving why your air conditioner heat mode is not working is to check whether something is blocking the airflow:

  • Move any furniture that might be obstructing the flow of air.
  • With wall-mounted air conditioners, check if drapes are covering the unit.
  • Check if something is hindering the outside (condenser) unit.

Air conditioner units commonly experience issues in heating/cooling due to insufficient air delivery, as the unit’s compressor can easily overload due to the lack of it.

Faulty Circuit Breaker

It’s important to remember that air conditioners are high-power consumption items. Here’s how much power they use compared to common household appliances and electronics:

DeviceWattage per Hour
Air Conditioner3,500

The current that an air conditioner draws from the power supply means that circuit breaker issues are not uncommon with these devices. For this reason, one of the first things to do when your air conditioner isn’t working is to check the circuit breaker.

Read: How Many Watts Does A Heat Pump Use?

Clogged Filters

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The lack of basic maintenance might be what’s causing the heating issue with your AC. Filthy and clogged filters are another one of the common causes for air conditioners to stop working as intended.

The good news is that you can clean the air conditioner’s filter on your own in just a few easy steps provided by GE Appliances:

  • Vacuum the filter carefully every 30 days.
  • Soak dirtier filters in a mixture of mild dish soap and warm water.
  • Soak heavily soiled air conditioner filters in a baking soda and warm water bath to remove grime and odors.
  • Dry the filters thoroughly before reinstalling them.

GE Appliances also underlines a couple things that you should never do with the AC filters. These are:

  • Never clean the AC filter in the dishwasher.
  • Never use the AC without reinstalling the filter.

The AC Unit Going Into Defrost Cycle

Some air conditioner models have a defrost mode that prevents the outside unit from seizing up during winter. Electronics can sometimes go haywire and hinder the device in returning to the regular heating mode.

If you suspect that this might be the issue, you’ll need to give a licensed and qualified air conditioning repairman a call, the air conditioning industry experts suggest.

How To Prevent Air Conditioner Heat Mode From Failing?

While diagnosing and solving all of those problems is fairly straightforward, we should focus on their prevention. Following the simple tips from this article, you can prolong your air conditioner’s cooling and heating life and spare yourself a lot of stress and money.

Here are a few things that AC users can do to ensure the heating function doesn’t leave them cold and stranded in the middle of the winter:

Regular Service and Maintenance

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Regular air conditioner maintenance includes:

  • Replacing or cleaning the filters.
  • Cleaning and inspecting the coils of both the outdoor and indoor units.
  • Checking for potential thermostat defects.
  • Inspecting the condensate pump and other vital elements of the system.
  • Cleaning and sanitizing the indoor unit.

Every homeowner or a renter should do their best to service their air conditioning device at least once a year. This service interval ensures that the unit is safe for use and keeps running the way it should.

While areas of AC maintenance, such as filter cleaning or replacement, can be done by anyone, it might be best to leave the more complex ones to professionals.

Read: HVAC System Service – How It’s Done And How Much Does It Cost?

Using the AC Heating the Right Way

Although it might seem simple, effectively using the AC for heating requires some thought.

The main thing to remember is not overloading the air conditioner for ductless systems, including the wall and window-mounted ones. This means starting the heating feature a bit sooner than you might need and gradually increasing the temperature as the weather outside gets colder.

Avoiding the turbo mode that some devices have is also my recommendation.

Refraining from constantly turning the device on and off is another way you can prevent putting too much stress on the air conditioner’s heater.

Following this simple tip will not only save you money when the electricity bill arrives, but it will also ensure that the air conditioner lasts longer.


Air conditioner heating is one of the conveniences of modern life we commonly take for granted. Being able to cool and heat your home with a single device was unimaginable less than half a century ago.

However, this convenience doesn’t come without its drawbacks. Relatively expensive to buy and maintain, air conditioners with a heat mode are also prone to breaking down.

Wrong settings, airflow constriction, electrical issues, dirty filters, and some of the unit’s technological features might be what’s preventing you from heating your home.

It sounds like you're delving into the nuances of air conditioner functionality, particularly concerning the heating mode. Let's break down the concepts discussed in the article:

Heating Mode in AC:

  • Purpose: It allows an air conditioner to both cool and heat spaces.
  • Benefits:
    • Offers heating option along with cooling.
    • Decreased power use compared to traditional AC units.
    • More effective cooling.
  • Drawbacks:
    • Higher initial cost.
    • Higher maintenance and repair costs.
    • More frequent service intervals.

Reasons for AC Heat Mode Failure:

  1. No Heating Option:

    • Check if the AC unit is equipped with a reversible system for heating. Review the user manual or remote control for indications.
  2. Wrong Settings:

    • Ensure the settings are adjusted for heating mode (set to HEAT, higher temperature settings, proper fan speed).
  3. Restricted Airflow:

    • Check for obstacles obstructing airflow (furniture, drapes, outside unit blockages). Insufficient airflow can overload the compressor.
  4. Faulty Circuit Breaker:

    • Air conditioners draw significant power, leading to potential circuit breaker issues. Check the breaker for any tripping.
  5. Clogged Filters:

    • Dirty filters hinder proper functioning. Regularly clean or replace filters per manufacturer recommendations.
  6. AC Unit Going Into Defrost Cycle:

    • Some models have a defrost mode; malfunction here might impede the heating function. Seek professional assistance if suspected.

Preventive Measures:

  • Regular Service and Maintenance:

    • Routine maintenance includes filter cleaning/replacement, coil inspection, thermostat checks, etc. Professional servicing at least annually ensures proper functionality.
  • Using the AC Heating Correctly:

    • Avoid overloading the system by gradually adjusting temperatures, avoiding turbo mode, and minimizing frequent on-off cycles.


  • AC's heating capability is a modern luxury but comes with added maintenance and occasional malfunctions.
  • Issues like wrong settings, airflow problems, electrical faults, dirty filters, and technological glitches can hinder heating.

The article provides a comprehensive overview of troubleshooting and maintaining air conditioners with heating capabilities, catering to various issues one might encounter.

Why Air Conditioner Heat Mode Not Working? - HVAC BOSS (2024)


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