No air flow in heat mode in passenger side

Hello sir, I have the car listed above (touring model) with single climate control. Recently I noticed I am getting no air flow in passenger side when I am turning on heat but when I am turning the dial back to low temperature air flow is back. Even when car is running passenger side is blowing cold air only. If I close the vents from driver side then I will get some hot air on passenger side. I checked the heater core and it is working fine as both hoses are hot. I checked all three actuators, mode control actuator, recirculating actuator and blend door (found in driver side) and they all are working as I saw them moving while I was changing temperature and modes. But for some reason air flow in passenger side drops to almost zero as soon as I change temperature setting from cold to hot. If car is running then there is some cold air coming in that side. Also, checked the antifreeze and it is full. Plus checked the radiator and it is working fine. Can you please help me out from this problem as it is minus thirty degrees here in Canada and it is very hard to drive with this.