$49 / month O.A.C Including Install
$49 / month O.A.C Including Install

Heat Pump Defrost Mode Explained

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Heat Pump Defrost Mode Explained

Posted On: March 9, 2026

Heat Pump Defrost Mode Explained

If you’ve ever noticed your heat pump stop blowing warm air for a few minutes during winter, you might wonder if something is wrong.


In most cases, it’s completely normal.


Your system is likely running in defrost mode, a built-in feature designed to keep your heat pump operating efficiently during cold weather.


At Twintech Heating & Cooling, homeowners often ask about this process when temperatures drop.


Understanding how defrost mode works can help you recognize normal operation and know when it may be time to call for service.


Why Heat Pumps Need Defrost Mode


During winter, a heat pump pulls heat from the outdoor air and transfers it inside your home.


While doing this, the outdoor coil becomes extremely cold.


When the temperature outside is near or below freezing, moisture in the air can freeze on the outdoor unit.


Over time, frost or ice buildup can restrict airflow and reduce the system’s ability to absorb heat.


If left unchecked, this ice can significantly reduce efficiency and heating performance.


Defrost mode solves this problem by periodically melting the frost from the outdoor coil.


How Heat Pump Defrost Mode Works


When sensors detect frost buildup on the outdoor coil, the heat pump temporarily switches into defrost mode.


Here’s what happens during the process:


The system reverses operation The heat pump briefly switches from heating mode to cooling mode.


Hot refrigerant flows to the outdoor coil This warms the coil and melts the frost or ice.


The outdoor fan usually stops This helps the coil heat up faster to remove the ice.


Backup heat may activate indoors Many systems temporarily use auxiliary heat so you don’t feel a blast of cool air.


The system returns to heating mode Once the frost is cleared, normal heating resumes.


This process typically lasts 5 to 15 minutes.


Signs Your Heat Pump Is in Defrost Mode


Homeowners often notice a few changes when the system enters defrost mode.


These are normal and expected.


Common signs include:


Steam or vapor rising from the outdoor unit


The outdoor fan stopping temporarily


A brief pause in warm air from vents


Clicking or whooshing sounds during the cycle


Auxiliary or emergency heat turning on


The steam you see is often mistaken for smoke, but it’s simply melting frost evaporating from the coil.


How Often Should Defrost Mode Run?


The frequency depends on weather conditions.


Your heat pump may enter defrost mode:


Every 30 to 90 minutes in very cold, humid conditions


Occasionally during normal winter weather


More frequently when frost buildup happens quickly


Cold, damp climates tend to trigger more defrost cycles because moisture freezes more easily on the outdoor coil.


When Defrost Mode Might Signal a Problem


While defrost mode is normal, excessive icing or constant defrost cycles could indicate an issue.


You may want to contact Twintech Heating & Cooling if you notice:


The outdoor unit completely covered in thick ice


Defrost mode running very frequently


The system struggling to heat your home


Ice remaining on the unit after the cycle finishes


The heat pump shutting off unexpectedly


Possible causes can include restricted airflow, low refrigerant levels, or a malfunctioning defrost control board.


Tips to Help Your Heat Pump Run Efficiently in Winter


A few simple steps can help reduce excessive frost buildup and keep your system running smoothly.


Keep snow, leaves, and debris away from the outdoor unit


Maintain at least 18–24 inches of clearance around the system


Change indoor air filters regularly


Schedule seasonal HVAC maintenance


Avoid covering the heat pump during winter


Regular maintenance ensures the defrost system works properly when your heat pump needs it most.


Professional Heat Pump Service


Defrost mode is an essential part of how heat pumps maintain efficiency during winter.


When the system is working properly, the process happens automatically and quickly clears frost from the outdoor coil.


If you’re concerned about frequent icing or reduced heating performance, the team at Twintech Heating & Cooling can inspect your system and make sure everything is operating correctly.


A well-maintained heat pump will keep your home comfortable throughout the coldest months while running efficiently all season long.



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See What Our Customers Are Saying:

by Jiri in Toronto on Twintech Heating and Cooling

From the initial contact we had an excellent experience with this company and all its personnel. Dave Gergley was an excellent, helpful, sales person and solicitous of our needs. He recommended only what was required and did not up sell or make any suggestions for products that we did not need, such as a new A.C. He explained the rebate process and basically outlined how to get the best furnace at the lowest price. When it was time for installation, the technicians could not have been more considerate, careful, attentive to detail, obviously committed to safety and optimum functioning of the appliance they were setting up. We have been perfectly satisfied with the functioning of the furnace and all aspects of acquiring it from the initial contact with Dave through to the installation process and follow ups inquiring about our satisfaction. Also they initiated the rebate process and contacted the appropriate inspection agency to carry it out. We highly recommend this company for all heating and cooling needs and we will contact them again when it is time to replace our A.C.

by Drew in Pickering on Twintech Heating and Cooling

Twintech was excellent from the initial quote and throughout the install. They had a competitive rate for hot water tank and ended up buying the tank from them, had them remove the old tank and install the new one. The day of install they were prompt and out in about 2 hours. Professional , courteous really great guys. We took a look at my 30 year old furnace and they were able to offer some suggestions for future there too.

by Harry in Toronto on Twintech Heating and Cooling

Ever since I turned on my furnace on Oct 2018 I hear a humming sound when the furnace fan kicks in. I called Adamson Air System who installed my furnace 7 years ago and couldn't figure it out the problem. I just wasted money to the guy who couldn't figure it out. I found Twin Tech via Amana / Goodman website. I checked the reviews from previous Twin Tech customers. I called Greg and was onsite on time this morning Sunday, Nov 25 2018. He figured it out what's wrong with the furnace and explained what the previous installer (adamson air system) did wrong when they installed it. His knowledgeable about his job. He recommend to replace the fun motor because the sound is not normal when it's running. Looking forward to see him again to replace the fan motor.

by Roger in Pickering on Twintech Heating and Cooling

Our house is over 22 years old and I had been researching furnaces and A/C brands for a while and thought it was time to take the plunge. After calling three different companies to come in and quote the job, this one won me over. From the first visit from Dave all the way to the end of the install by Greg, Grant, and Piotr, I was glad to have picked this company. Dave was very knowledgeable and really took the time to explain what kind of quality installation I was going to get as well as showing me some of their previous work and certificates.

I was also surprised at how quick the installation took and how nice everything looked afterward, I mean it's only a furnace right? They even re positioned the furnace so that I have easier access to my filter and humidistat, awesome! If you are looking for a company that cares about their customers and is proud about the quality of work they do, along with a great and competitive price, then stop right here because you found it.

by Louis in Pickering on Twintech Heating and Cooling

Once our AC Unit started to fail, I called our past Heating & Cooling provider for support. The response was we needed a new motor for our Furnace. It was time to check their Quote against the marketplace, I reached to other providers online. One of the owner of Twintech (Greg), called me and offered a preliminary Quote and recommendation online. The others needed to set an appointment and came to measure and spend 1 hour before offering a quote. Then I asked Twintech to come finalize their quote to make sure their recommendation was aligned and met our needs.

Twintech was professional throughout the process, easy to deal with (Web, Phone and in Person), price right and met their commitment. Their team expedited the process and installation, arranged for a energy assessment for available rebates and most importantly, delivered on their commitment and managed to do a few extras. They installed a New Furnace, AC unit and Nest thermostat in a day, remove all older units, left the house and outdoors clean and without any debris. Great to be able to support a Local Company, Neighbour and Professional team - Well Done Team Twintech !!!

by Elizabeth and John L from Scarborough on Twintech Heating and Cooling

In October 2018, I contacted Greg at Twintech to do a furnace cleaning. Greg discovered that my furnace, installed in 2006 by another company, had been installed incorrectly, leading to restricted air flow. The heat exchanger was also defective. As well, my furnace was too large for the size of my house.

In my opinion, the biggest concern most of us have as consumers is that we have no idea of the quality or knowledge and experience of the technicians any heating and cooling company will send into our homes. I could have avoided having my 2006 furnace installed improperly (leading to early replacement), had I known about Twintech then.

With Twintech you get it all. Because Twintech is a smaller company you can rest assured that the only technicians who will work in your home are Greg and his twin brother Grant who are co-owners and fully licensed and certified with over 30 years of experience in installing and servicing heating and cooling equipment. They are both friendly and personable and answer all your questions. Their workmanship is outstanding. We had a 2 stage, variable speed Goodman furnace installed. My wife and I noticed a difference in the heating and even temperature of our 2 storey home almost immediately. Our old furnace always heated too much on the main floor and too little upstairs. We are also impressed with how quiet the furnace is.

Twintech's office manager, David Gergley, is equally friendly and not only gave us a competitive quote to replace our furnace (we sought other quotes), but also went above and beyond my expectations when he made arrangements with an energy audit company so that we would be considered for a grant from Enbridge and IESO.

Needless to say, I give Twintech a 10 out of 10 and highly recommend them!

by James, Ajax on Twintech Heating and Cooling

Clean, Fast and Efficient Work. Between all the quotes I received Twintech was a few dollars less and offered the best warranty.

by garysumnec360, Whitby on Twintech Heating and Cooling

They did an excellent job. Everything was very well explained. At the end of the job everything was very well cleaned up.

by Glade, Pickering on Twintech Heating and Cooling

Twintech offered me a competitive price but more importantly great sales and installation service. They did everything with attention to detail and quality workmanship that is hard to find in this day and age. Dave who first game to visit me answered most of my questions and probed about my needs. For the technical/install questions he was unable to answer he quickly had Greg and Grant the owners answer for me. They did not cut corners on the installation or do anything to simply save time. They stayed into the early evening to complete the job and removed all my old components and even fixed up mistakes other workers ahd made in the past. I would highly recommend them and use them again if the need arises in the future. If you are looking for service or new equipment I would highly recommend Twintech be on your list of Heating companies to get a quote from and ask your questions to.

by Anne of Major Oaks in Pickering on Twintech Heating and Cooling

The company epitomizes high quality service: from the initial client interaction with Dave to the installation and follow up with the technical team. One of the key features I look for is the ability of a technical person to talk to and not talk down to the customer when responding to questions and I had quite a few, all of which were very professionally addressed. I was also quite impressed with the follow up service, promptness, the obvious competence of the team who left no stone un-turned to ensure I was a satisfied customer. Thank you guys.

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See What Our Customers Are Saying:

by Aaron on Twintech Heating and Cooling

We are very happy to recommend this company to everyone. Our furnace broke down on Sunday morning. We phoned them and before noon Grant the owner showed up. He worked on the furnace for about a hour not wanting to give up to fix the problem. The furnace was 17 years old. I was the one talking about replacing it. End result was the next day it was all done. On the Sunday Bob came over with heaters to warm up the house. We decided to replace the water heater at the same time. Thanks Grant for the excellent work. Thumbs up.

by Linda on Twintech Heating and Cooling

Right on time. Explained how to work the HRV in a different way so the house would not be so dry. Changed my whole house water filter for me as well. Friendly, helpful, caring service!

by Robert Rogers on Twintech Heating and Cooling

Very pleased with the professional service that TwinTech Heating and Cooling provided in replacing my furnace. I got several quotes from different service providers. Their price was excellent and they explained the features very well. We are very glad we went with TwinTech and highly recommend their services.

by Robert Mizuno on Twintech Heating and Cooling

We were new homeowners in need of a second opinion. TwinTech Heating & Cooling were Amazing and professional. Very knowledgeable and great service all around. Recommend to anyone looking for honest and reliable services. Treated with respect and care. Thank you Greg, Mitch and Bob!

by Ruth on Twintech Heating and Cooling

TwinTech is an excellent and honest company! I called them for a second opinion after being told by another company that I needed to replace my furnace. Turns out this was not the case at all! I did not need a new furnace. TwinTech did not push to make an unnecessary sale and saved me from a huge expense. Bob and Mitch were extremely professional and above all honest! I definitely recommend TwinTech!

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