Running Your AC in Winter: Yes or No? All Your Questions Answered

Almost every home has an air conditioner these days, running at full tilt during the summer months. And why not? We all want to remain cool and comfortable. But with winter now just around the corner, it’s probably time to forget about these appliances and wait for next summer. Or not? In this article, we cover how you can run your AC in winter and answer all your concerns!
While most of us believe that an air conditioner only works to cool a room down, that’s not entirely the case. Modern air conditioners can regulate the temperature according to your liking, both in summers and winters. The air conditioner simply reverses its function, allowing the AC to run efficiently during winters, thus throwing warm air in the room. On a side note – speaking of efficiency you may be interested in making your air conditioner smart for energy savings and comfort – whether summer or winter.
Even though air conditioners work in winters, there still are some safeguards that we need to keep in mind for effective heating. If you’re planning to use your ductless air conditioner during winter, you’re in luck. We’ve compiled a list of frequently asked questions regarding running air conditioners in winter to help you out.
Can I Run My AC in the Winter?

The answer is a most definitive yes. In the case of a reversible air conditioner or ductless heat pump, it makes sense to use the air conditioner all year round and enjoy the heating function. In fact, ductless heating systems come with a lot of advantages.
Even if your air conditioner is not a reversible one, you may still find some use of it during winters. If your room is getting too stuffy and suffocating due to heating, you could turn on your air conditioner in fan mode and make the room a bit more comfortable to be present in.
Keep in mind, however, that even if you can use your air conditioner during winters, the efficiency of the air conditioner will be different as compared to summertime. This is because even though an air conditioner is operable during winters, it is designed for use when the outside temperature is higher than the indoor temperature.
When Does It Get Too Cold for an Air Conditioner?

Just like humans, and other home appliances, air conditioners also have a minimum threshold for their operation, below which they would not be able to work as intended. Whatever the air conditioner brand or model or type, there would be a minimum limit for the operating temperatures.
Generally, the minimum outdoor temperature is around 60 degrees Fahrenheit for an AC to work. Below this temperature, the refrigerant starts behaving differently, and the AC does not work as intended. Running the air conditioner below this temperature can result in damage to the appliance, such as:
- Freezing of refrigerant coils
- Thickening of lubricant
- Damage to moving parts and bearings
How to Run AC in Winter?

With furnaces and ducted systems leaving a dent on your utility bills, you would want an alternative that is just as effective in heating, but not as hard on your pockets. Instead of having a separate appliance for heating, what if you can do both heating and cooling with one appliance?
That is exactly what a reversible mini-split heat pump does. You can use the same appliance, with the same energy-saving features throughout the year, to keep you cool in the summers and warm in the winters. Other than a mini-split, there are many other types of heat pumps available on the market too.
How an air conditioner works is by transferring heat from a hot environment (indoors) to a cooler one (outdoors). This is all well and good in the summers. But in the winter months, you want to get the heat from outdoor and transfer it to the indoor. The air conditioner has to work in reverse.
To get your air conditioner to do that, a little device known as a reversing valve is used in heat pumps, and heating functionality is achieved.
Freeze Protection Mode during Winter
Freeze protection is a mode that some air conditioners provide. This is also known as min. heat, low heat or 8o C depending on your air conditioner. It is extremely useful for places that experience extreme cold. The AC runs at a low power setting where warm air is continuously introduced into the room. This feature prevents the room temperature from falling below freezing or reach near freezing point. This is helpful in preventing damage to sensitive electronic equipment, water pipes, or paintings at a very low operational cost.
Will Running AC in Cold Weather Damage It?

The answer is not as simple as yes or no. There are many factors at play, and running AC in winter is not without risks. With moderately cold temperatures, an air conditioner is perfectly acceptable to run in any mode whatsoever. But with temperatures below 60 degrees Fahrenheit, there is a risk with putting the air conditioner to use. Let us go over some of the problems one by one:
Loss of Lubrication
Compressors are an integral part of the air conditioner and need to be in perfect shape to keep on running as desired. To aid in their smooth operation, lubricants help the compressor to function without any fault. In the winters, though, this lubricant can thicken and not function as desired. Without proper lubrication, the compressor is prone to damage and seizure.
Low Ambient Temperature Sensor
Most modern air conditioners come with a low ambient temperature sensor. This is done to prevent air conditioner operation during extreme cold and prevent damage. If you try to circumvent this sensor and turn the air conditioner on in-spite of the low temperature, there can be very costly repairs that would need to be done.
Overheating Compressor
As with any mechanical device, a compressor heats up the more it is put into use. During extreme cold, a compressor would need to work overtime to keep the interior warm. This can lead to it getting overheated. Using the air conditioner below the minimum specified temperature can irreversibly damage it, or at best, become a cause for significant repairs.
Freezing of Cooling Coils
While an air conditioner is in use, you may observe water dripping from the outdoor unit. This is condensation from the outdoor copper coils. In the winter months, this condensed water can freeze over the coils, and accumulate on them. With ice frozen over the coils, air does not heat up to be thrown into the room. All you will feel is cold air coming out of the louvers.
Moreover, freezing in the outdoor unit can damage it. Running the air conditioner while it is frozen can puncture the cooling coils and then require a replacement. To prevent this, keep the unit off and allow it the ice to thaw for a couple of hours. You can make the process faster by pointing a hairdryer or hot air blower at the outdoor unit fans and vents.
Measuring Heating Efficiency

Much like how you measure your car’s efficiency in miles per gallon, you measure the heating efficiency of your air conditioner using the Heating Season Performance Factor, or HSPF for short. A higher HSPF translates to a more efficient heating system, resulting in lower energy bills.
HSPF calculations compare the total heat provided by an air conditioner during the heating season with the total amount of electricity used. By using the values of heating output and electricity consumed throughout the season, it is ensured that outdoor temperature variations across the whole season are accounted for.
According to the United States Department of Energy, the minimum HSPF for residential air-source systems is established at 8.2 HSPF. High efficiency systems can run up to 13 HSPF, but somewhere around 10 HSPF is considered adequate.
Final Thoughts

To wrap it up, running AC in winter is the sensible choice with modern air conditioners. With a reversible air conditioner, the benefit is obvious, you can get hot air into the room. But even with a non-reversible air conditioner, you can get a whiff of fresh air in a stuffy or hot room.
But be careful when running the air conditioner in extreme cold, as the outdoor unit can freeze over.
With these checks and considerations in mind, you now know how to run AC winter, and are all set to use your air conditioner in winter!