heating problem

[Cabin_Guy]

HI,
I have a 2005 Unlimited and it seems to only want to be on defrost. The switch to redirect the heat feels ok ( ie" doesn't feel broken or stripped when I turn it) but no matter where I set it, it blows on defrost and my toes get cold!
I have no idea how the switch makes it do what its supposed to do so thought I'd ask here before starting to rip my dash apart. Wondering if its just a relay or something?
thanks for any advise.

 

[SteelHeadz]

It's a vacuum issue. In the engine compartment, look for a small black vacuum line that goes thru the firewall on the passenger side where the A/C lines goes thru the firewall for the evaporator. There should be tee connector where one end goes to the intake manifold and the other , under the battery tray to a vacuum reservoir. A small leak from this line will cause the HVAC control head mode operation to fail.

 

[Cabin_Guy]

ah, that sounds nice and easy, I'm glad I asked before tearing my dash apart !!
Thanks so much.

 

[Cabin_Guy]

OK, I found the line that goes into the firewall and as you said it T's off one way to under the battery... but instead of going to the intake the other part of the T goes to the drivers side,and T's again, one end going to the cruise control and the other ( with a boot on the end) goes nowhere. I have looked all over to try and find where this boot fits on but no luck. I would think it should go to the intake but its pretty greasy and my engine is very clean so it doesnt look like something that came off the intake.

any advise?