I've got ducted air con through-out the house. House is about 15 year old and has a security-grill in ceiling so that you don't need to have a door or window open. Even if I turn the air con down to 50% fan and a window open in another room, internal door shut, I can't close the glass sliding door. My dogs can open screen doors so with the kids I get them to close the glass doors so they are constantly being used. Is this a normal problem with glass sliding doors and ducted air-con?