AC gremlin.

[91grandmarquis]

Ok so heres the dealio...

The one on the right is getting vacuum when AC is in on position be it max or normal.



another pic of that one.



This one I have no Idea about and cant feel it move at all. Do you suggest pulling a vacuum on this one and seeing what happens? (referring to the one on the left that is a lighter color with yellow vac line.)




And the ford parts guy gave me these, someone may find them useful, feel free to add them to a sticky or what not if you want.





Im pretty much dead in the water until I either get someone who knows what is going on, or get it diagnosed. The guy said he sells a lot of part #19E624 and that is an ac speed control resistor? It is $209. the ATC is $24 and that is the circled part on the paper #19C734

[sly]

I think you're looking at the vent actuators (vent, floor, mix, def, etc). The blend door should be all by itself further up in the ducts. It may be one of those setups that blocks the heater core coolant flow for cold and releases it for heat. If you loose vacuum the heat opens up (had that problem with my car and replacing all the check valves in the AC vacuum system fixed it - added a GM vacuum ball for good measure too). It may also have one of those electric blend door motors. Not sure about the 91. I know my 88 has a really BIG vacuum actuator on the blend door that you can see just by taking the glove box out.

[91grandmarquis]

So what does the blend door I need to look for look like then? I guess I am just confused.

[cadfan64]

Dave's first pic is the servo, that is what gadget wants you to apply vacumn to. If you apply vacumn to it, the outlet air temp should go full cold. If it does, then you need to replace the sensor , which is in Dave's second pic, and you have to remove the dash pad to get to it.

The sensor is around $60, can get it from Rock Auto. Fairly easy to change once the dash pad is off.

[87gtVIC]

All true^ But what we are discovering is that the new dashes have different configurations. We need a translator to help us figure out what is what.

[91grandmarquis]

Ok mind you this is my two cents, but is it possible that on a 90-91 it is not vacuum controlled? It seems the blend door is that black box with a white colored top correct, and the servo is on top with a vacuum line connected. Mine seems to have a servo, however I cant find any vacuum lines to it and the box holding the door itself is a little different if we are referring to the box in this pic.



If that box is the blend door then I am thinking that it is not vacuum controlled. I can barely see a kind of servo ish looking white boxy thing on the very top.

[91grandmarquis]

So this is what appears to be the servo....

[cadfan64]

OOOOO the devils changed the system...probably, the Ford guy was right..sawwy for the confusion. Bet your "servo" is electronic and that would be what you need (the circled part on your Ford pic)

[91grandmarquis]

He circled the ATC sensor for me.. If your referring to the schematic. Its $26 dollars, but Ill have to yank the dash... and Im not sure Im up for that right now, although its just going to get hotter. I hope that will fix the problem. Is there any way I can open the vent manually just to be sure, since pulling a vacuum is out of the question.

[sly]

here's some sites with info on the electric servo blend door thingy

http://www.blenddoorfix.netfirms.com/

http://www.conceptualedge.com/blend-door/

it's based on the exploder but should translate over pretty well.

[gadget73]

hmmmmmm well the thing he circled does appear to be the ATC sensor. Its got all the earmarks, though the determining factor is if it has vacuum lines connected to it, or if its got wires connected to it. If you have wires, you have an electronic blend door servo, which is what the aeros got. Those go bad. If it has vacuum lines, then its the vacuum controlled system I'm familier with, and about all that really gives out on those is the sensor, or vacuum leaks.

The small cans with the colored lines are what change things from dash to floor to defrost.

http://www.lincolnsonline.com/tech/00175.html

That has pictures of the blend door servo used on early aeros. Not sure about anyone else, but I'm thinking the white box of electronical failure is what I'm seeing under his dashboard on top of the air plenum. When those die, the temperature wanders from hot to cold, so you do have the symptoms.

[91grandmarquis]

so at this point its either the servo or the sensor depending on the vac lines. The guy I got the car from said it was the blend door. Ill have to yank the dash at some point.