The air flow from the heater/ac sometime works other times won't. The blower is working OK (runs) but no air is comming out the vents. You can hear the fan blowing some small amount comes out the side defrosters. It appears as if a door from the outside is not opening. Next time the car is started everything may work OK. complete control. the same for A/C. Is there any diagrams on the heater/blower assy.?