Central Air Conditioning should never be operated in cold weather. This can cause serious damage to the compressor unit. You should not use your central air conditioner unless the outdoor temperature has been above 65 degrees for at least 24 hours.
Remember to uncover the unit if it has been covered over the winter months. At the start of the cooling season, when you are about to start using the air conditioning unit, you need to make sure that the power is on for a minimum of 24 hours.
The thermostat should be switched off, and left off for at least 24 hours before operating the Air Conditioning Unit.
Most condensing units have a compressor crank case heater that allows a heater to warm the crank case lubricant. When the compressor crank case is cold, the coolant can be partially absorbed into the lubricant. This will result in frothing of the lubricant, and can cause undue wear on bearings, etc. Turning on power to the unit at least 24 hours before use will allow for the crank case lubricant to heat up and will release any coolant absorption from the lubricant.
After a minimum of 24 hours, the unit can be run safely. so, the net is... Just make sure that the power to the air conditioning unit is on at least 24 hours prior to using the air conditioning.