What you are hearing is the Refrigerant inside the system boiling as the temperature changes throughout the day.
As the temperature rises, the pressure inside the system rises and has a effect on the refrigerant. Also as the temperature lowers, the pressure in the system lowers and also has a boiling effect on the refrigerant.
You have no worries.
Please hit ACCEPT if you are satisfied with this service.
Okay, and thank you for your response, but I am still concerned...I have had this air-conditioner for 6 years and it has never done this before. It has had a cool down cycle occasionally, but this is happening now when it is not in use or turned on. Our temperatures seem to be the normal range of what we get every year. My biggest concern is a fire hazard when we are not home. Should I be unplugging it every time we leave our house. It sounds like a motor is on....fan like sound...no air coming through front vents...definitely sounds like an internal cool down system over working....not able to accomplish it's task. I would say it is happening every hour...even though we are not using it. Could the refrigerant system be going bad?
Is this a window unit?
No....an installed into wall unit....but I am sure it could have been installed into a larger sized window. ;-)
I purchased this unit from Home Depot 6 years ago and had it installed by a carpenter into my living room wall. We have never had a problem until now.
Is the fan coming on?