Hello, I have a 2001 F150 4x4. It does not have auto climate control.
I know I have a vacuum issue with my A/C, which causes the air to come out the defroster vents only.
I have removed the controls from the dash and removed the vacuum hose harness from the back, and do not have vacuum there.
I have located the check valve and tee behind the battery, and am good up to here.
I have checked the reservoirs behind the battery.
However, with the engine off, and the vacuum harness unplugged from the dash control, I can neither blow, or suck any air through the hard plastic line going from the tee into the firewall.
Can someone tell me where the hard plastic line going through the firewall runs to? Worst case scenario, I can run a new line from the tee, but I can't seem to find where it is supposed to conect....
If anyone and a decent vacuum line diagram of the A/C system, I think it would be a big help also.....

 

What controls do you have? Digital or rotary?

 

I have the rotary controls.

 

Can you hear any vacuum leaks under there? Have you checked the vacuum actuator for the blend door?

 

No. I cannot hear any vacuum leaks. There is no vacuum on the blend door actuator, and there is no vacuum on any of the five vacuum hoses attached to the back of the mode control. I am fairly certain there is some sort of blockage in the hard black plastic line that goes through the firewall. I just don't know where, and what it connects to underneath the dash.