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.

 

[MobyDick]

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

Ok, so it is NOT the blend door. It's some sort of "flap" in that evaporator case.

 

[slowmkviii]

So what is your problem heat/ac or direction of air

 

[MobyDick]

The heat and AC work, but when you switch between the two, the "flap" will not move. I either have to have heat or AC. Make sense?

 

[slowmkviii]

If you don't daily drive it I'd take the blend door actuator off and see if the door moves by hand
If you need the actual door you will probably have to get one used

 

[xtriggerman]

The blend door arm (#16) is very brittle and they all break. In addition to that, the lower door above the passenger floor that connects to the brittle arm via #18, has a very specific amount of arm swing movement. The blend door arm motor is faulty in that it provides too much movement to the lower door. This binds the lower door hard against its shut position and there for breaks the blend door arm. this is the case in ALL gen 2 cars. If by some odd chance yours is not broke, it will be at some point. Here are my articles on it on how to modify the arm as to overcome the binding. Thankfully, China steped in and now make replacement arm and motors as indicated in the article. From your description, you have this problem. Some that dont want to get involved with all this put a wire on the lower door arm and tie it to the hot side or the AC side depending on the time of year. The proper and final fix is in the articles. Best of luck with it.

Ultimate Blend Door repair & modification / * UPDATE *

Being a trained Gunsmith, rule #1 is before you can fix any thing, you need to know exactly how it was designed to work and why it failed. That's why I have tried to explain this repair to the extent that you need not piece together bits of info...

www.lincolnvscadillac.com

Part 2 Ultimate blend door repair FINALLY 8/22/20

**** UPDATE*** Well folks the earlier Ultimate blender repair article on making the repair & mod of the black broken arm is nearly all but worthless. My above repair lasted a little over a year and the stud on the black arm has snapped off like...

www.lincolnvscadillac.com

Oh, I guess the best way to check the door is to remove #18 from the lower grey arm and manualy swing it in both directions. It should have a defined stop in either direction. If it can spin around with out a hard stop in either direction, then your door is broken. One other guy had that grey door arm broken. Thats the odd one. Most all are broken black arms up on the motor that have been reported over the years.