AC Stuck on defrost

[Warren99]

Just as the title says, my AC is stuck on defrost. It's not charged with freon yet but don't want to try it again until I get it fixed. Blower motor works fine, the heater works too, not the best but what can you expect. No matter what setting I have it on, all of the air is directed to the defrost vents. I can't feel anything from the panel vents, if its bleeding thru them some, its so little you can't tell. Is this at all common? I have the jeep 1989 service manuals and found a diagram of confusing vacuum lines and doors/switches. Before I decided to take the dash apart I'm coming on here for opinions. 

[eaglescout526]

Common issue. Check your vac hardlines to and from the vac reservoir behind the bumper. They rot easily. 

[Warren99]

I think I've actually seen an unconnected line somewhere around there, could you be more specific?

[JStone]

Having the Same issue, ive been meaning to get on and ask about this! So thank you for this, cause ive heard the vac system needs repair if this is an issue, I'm not really sure why that is. 

I've also heard that the vac cannister preforms better if set closer to the back firewall, is that true? Does it also require a lot of re routing of the vac lines?

[Warren99]

Just checked and only found two lines. The source one has plenty of vacuum and neither seem rotted. Nothing changes except the engine idle ofc when either are unplugged. There are two wires hanging, maybe they need to be connected I'll check that in a min, here's a pic of it all.

[Warren99]

Ok so those wires are for my missing second horn. Also I think that would be why my other horn is very weak and choppy, it might need the second one to complete the circuit, either way I'll look into that later.

[jdog]

What happens when you connect the two lines together?

[Warren99]

As in bypass the reservoir?

[Warren99]

I did that and nothing changed

[scaleless]

I guess if you have a good vacuum there, try manually moving the doors connected to the vacuum actuators.  I don't remember which is which, but maybe one is seized up or a vacuum line is pinched?

 

If you feel like removing the AC controls and have a vacuum pump, you can test the controls at the connector:

[CGCWO]

Following as I have the same problem.

[cruiser54]

[JStone]

So I’m guessing your saying that somewhere in the diagram you just posted that there is a break or some sort of malfunction? 
I will dig into it this weekend and let y’all know what I find, 

[cruiser54]

Yes

[AZJeff]

It has been my experience that most of the leaks are going to be in one of three places:

 

1.   the vacuum hose (and nipple) where the vacuum reservior is located

2.  the vacuum hose where it travels under/near the battery tray

3.  any of the in-iine vacuum hose fittings/"Tees" that head towards the manifold or the heater box

 

Focus on those first, and then expand your inspection from there.   Its not complicated, just tedious. Good luck.

[Warren99]

Alr thanks I'll come back with the results tmr.