HVAC part question

[MobyDick]

Hi all,

I need some help identifying and locating a part for the HVAC system for my 98 Mark. I'm being told that the part number is F7LZ19850AA, which is the evaporator. However, the shop is saying that the issue is inside the box. There is a flap that turns only when it wants to, and that the "right" way of repairing it is to replace it, so I need the whole box. It's the HVAC box that goes under the dash where the evaporator core goes.

I attached an image they sent me for reference. Can anyone tell me what to look for on RockAuto, eBay, or whatever?

 

[slowmkviii]

You need to figure out what part is actually bad
The normal one to go out is the blend door actuator that is #14 and if that what actually bre #16 and or 17

 

[slowmkviii]

Both 16 and 17 can be seen from under the dash left and up from the glove box

 

[MobyDick]

I have two spare blend door actuators if that's the problem, but why did they circle those two parts saying the need the whole "box"? I will ask them today.