is this correct center vent operation

[jsmith]

i don't get any warm air through the center vents until the the climate control setting is reached. warm air always comes through the side vents. this does not affect a/c or when cool air is called for. i discovered this by lowering the temp setting which starts air coming out from the center vents. i.e., i turn it to about 70 to warm the car quickly - i won't get any flow from the center until it hits 70, if i turn it down to 65 then air will start flowing...