There could be any number of reasons why someone may want to run their AC during the winter.

By winter I am suggesting the cold season being anytime from October to March here in Toronto or the GTA.

For example, it could be when you are hosting the’ turkey dinner and the oven plus the burners are on along with extra family members and friends, your house can turn into a sauna.   You very well could here someone say “it’s hot in here, can you turn the AC on?”.

Alternatively you may experience a lot of humidity at a point during the winter where it collects on your windows and turning on the AC would be an effective way to remove that water vapour.  Sure you may have checked the fan to ensure its not blocked up with snow, or maybe you have a cover and simply removed it so you can fire the air conditioner back up temporarily.

It’s not like you can’t run your air conditioner in the winter, it more that you are running your system outside the design parameters.  All the repair techs here would strongly advise against it.

Nowhere in the owners manual does it give specific instructions against running your air conditioner in the winter, but they do elude to it.  Take a look at some of the charts showing efficiency, you may quickly find the lowest temperature shown is around 60 F (15 C for Canadians).  The charts only show so far as most home owners would simply open their windows rather than running the air conditioner.

On top of common sense many air conditioners are equipped with factory installed low ambient controls to prevent operation in low temperatures.

In terms of harm you can cause to your air conditioner… The compressor can overheat as the oil is too think to circulate in cold temperatures, causing the unit to fail.  If this is a rental air conditioner there is a good chance the company renting to you will hold you accountable for running the system during the winter.

Primarily you would simply want to open your windows to cool your home down in the winter months.