Omni HVAC Problems

[5.8LImportEater]

I have a 86 Omni that has some problems. The car sat for 2+ years, and has only a little surface rust. The interior is perfect except this. The HVAC is having problems lately. The first problem is the temp slide is not working now that it has been stuck on cold for 4 months. I don't know whether the cable is rusted, or one end or the other is not moving now. What is the most likely cause of this?

Next problem, the HVAC is not moving the air to any other vents except the dash. I removed the panel and made some jumpers from vacuum tube and could manually make the system work. so there are no vacuum leaks that I can find. Do the HVAC controls on these cars break commonly? I really need to get this thing working here before cold weather gets here.
Chris

[detobias]

the plastic vacuum connectors and lines get extremely brittle then crack and leak

it may be easier in the long run to replace all the vac lines at once, otherwise you may be chasing your tail

[NAJ]

Disconnect the cable on both ends and see if it moves freely, if the temp control lever moves on the control unit and if the blend door moves.
Be sure you have engine vacuum to the control unit, if not repair the vacuum line issue from underhood to control unit.

[5.8LImportEater]

The last time I took the dash apart, I had vacuum at the little "tree" that holds the lines at the back of the HVAC unit. I then took a spare piece of that tubing and manually hooked up all of the other controls one at a time to the vacuum line port in the tree, and could make all of them work. I am "pretty sure" that I don't have any vacuum leaks from the motor to the HVAC, and from the HVAC to the vacuum canisters that move the doors that direct air, I also don't have any easily detectable leaks, as everything will work if you make a direct connection between the two holes in the tree. Basically I "think" that the problem is in the HVAC controls, and wondered if there is an easy fix, and if not, what controls will work in an omni?

Oh, and yeah, I don't think the cable is working for the temp slide. I will probably have to get a new one, are there any cheap/easy ways to do this? or do I have to stand on my head?
Chris

[NAJ]

There are only 4 possible causes.
Vacuum supply in, should be engine vacuum.
Vacuum supply out, should be engine vacuum at each door actuator when selected.
Faulty vacuum actuator, connect a vacuum supply such as hand held vacuum pump and apply vacuum, actator lever should retract.
Stuck/Broken Mode Door, remove actuator and see if door moves freely by hand.
Disconnect the temp cable on both ends, does the control unit slide move? Does the cable move by hand when disconnected on both ends? Does the blend door move freely?
Do not know where to get the temp control cable, check your dealer first and if discontinued ask them to run a parts locator or get the part #.