Ac blowing out defrost

[Richard Flickinger]

I notice that the ac switches back and forth from vents to defrost. Been trying to figure out whether it's a vacuum problem or an electrical one. It's an 01 sport trac.
I been trying to find a good vacuum diagram also.
Any suggestions.

 

[koda2000]

You have a leaking/broken vacuum line. When you loose vacuum the defroster vents are the default setting for the HVAC directional controls.

Most all the HVAC controls work off vacuum. Begin by checking the lines going to and coming from the vacuum reserve ball, which is located in front of the passenger side front wheel, behind the plastic inner fender liner. Follow the lines where ever they go to find your leak.

 

[Richard Flickinger]

Thanks. I will try to locate it and check. Will try to repost if I find the problem there.

 

[Richard Flickinger]

can this also cause some of the lean code 0171/0714 to activate the cel. been battling that issue also. just changed the upper and lower intake manifold gaskets this weekend, code came back. i was running the ac on max

 

[koda2000]

can this also cause some of the lean code 0171/0714 to activate the cel. been battling that issue also. just changed the upper and lower intake manifold gaskets this weekend, code came back. i was running the ac on max

Yes, a vacuum leak can definitely cause P0171/P0174 DTC's. It doesn't matter whether your A/C is on or not, but the fact that your HVAC blows out the defrost vents is related.