How long should I wait before turning on my window AC?
You should wait 8 hours before turning on your window AC if you’ve moved the unit or had it on its side recently. There’s no need to wait before starting your window AC if you haven’t turned it on its side.
We recommend waiting as long as you were moving the unit. So if you’re just moving the unit from one room to another, a 30-minute wait should be plenty. Wait for 8 hours if you’re moving it between locations or if you’re starting it for the first time.
Alternatively, follow any guidance offered by your manufacturer. They know more about their specific unit than we do. Also, you risk voiding your warranty if you don’t follow proper installation procedures.
The reason why you need to wait before turning your window AC is to let the refrigerant and oil settle back into their proper locations. The oil that lubricates your window AC’s compressor will sometimes travel up the lines if you rotate the unit more than 30 degrees.
As the oil travels up the lines, some refrigerant may fall down into the compressor. Starting a compressor without enough oil runs the risk of damaging the component. Avoid damaging the compressor at all costs as it’s the “engine” of your air conditioner and very expensive to replace.
The compressor is responsible for maintaining a pressure difference between the refrigerant in the condenser coil and in the expansion coil. A compressor is basically a pump. That difference in pressure between the two coils is the reason the expansion coil is cold enough to cool your room.
It’s worth knowing that there’s a difference between window ACs and other types of air conditoiners like split AC or in-wall AC units. Split ACs are permanent installations and aren’t designed to be moved frequently. As such, you want to let them sit for 24 hours before starting them.
In addition to the problem of oil movement, the compressor in a split AC or in-wall AC actually has to be warmed up by a small heater before you start it for the first time.
Portable ACs and window ACs are designed to be moved. You can start them immediately if you haven’t rotated the unit. Most people start them without any rest period and have absolutely no problems. But, it’s best to follow our guidance and be safe rather than sorry.
Mark is a journalist who has written about home products for two years. He holds a masters degree with distinction from the London School of Economics and an undergraduate degree from the University of Edinburgh.