Hello. I'm a total newbie homeowner. Bought a 20 year old house with this type of hanging A2A heat exchanger. Trying to figure it out. It runs fine and I've cleaned the filters and the big black box. But when I turn it off at the upstairs control shouldn't the electric intake damper close, so that the cold air doesn't come in. I'm in Canada with cold winters and sometimes the box gets cold; I open it up and the intake is open even when it's not running. I opened it when it was running once and it stopped (since the button wasn't depressed). Then when I pressed the button manually the little motor ran and the damper door closed about halfway and then retracted. Sorry for the long explanation but when is that door supposed to close and how can I check if it's working properly. Thank you!