1993 Mustang Ac Stuck On Defrost

[Sun Dropsz]

It all started when I was trying to figure out why my AC won't blow cold air. I took the control unit off to look at it and test it with my multi meter. Put it back together then I noticed I got it stuck in defrost mode. One problem after the another.... I read up on some forms on here and most people said its the black tube that goes through the firewall. It doesn't have any cracks in it but it doesn't want to fit where it needs to fit! It's not tight as the other lines. I went up to orileys and asked them if they had any tubes like this, they had no idea what I was talking about. Where can I buy new tubes at, I've looked everywhere and can't find anything. Would I be able to go a junkyard and pull one off a older f150 or explorer or something?

Here some pictures of what I need to buy. I cant find out what they're called.

 

[Mustang5L5]

There's a single black vacuum line that runs from the vacuum block, into the interior of the car. It usually connects to the hvac controls right behind the center console stack area on the driverscside. There's a union from the vac line from engine bay and the vac line from the hvac controls, and this usually falls off.

Here the line in the engine bay

 

[Mustang5L5]

Also, the yellow vac line is what controls defrost and the panel vents. If this pulls off, it goes the defrost only

Here's its location on drivers side area under dash

 

[General karthief]

You didn't say where you were having the loose connection problem, at the hvac in the panel or under the hood at the tree.
Do you have vacuum to the hvac in the panel?