AC blowng through defrost only
 

Apparently this is a common issue on these cars as age catches up to them. Mine started blowing cold through the defrost vent only. Cycling the switch was no help. I did a quick isual inspection under the dash, and what little I could see didn't really show any apparent issues. In consulting the all knowing You Tube, it became apparent I was looking in the wrong place. After a quick clean up of the vacuum hoses underhood, it became very apparent the a hard plastic vacuum line had serious cracks in it. I put my finger over the cracks while the car was running and the AC began to blow out of the proper vents. I later taped them up with electrical tape as a temporary fix, and I'll cut it later and add a section of soft vacuum line or fuel line for a more permanent fix.

:borg:

Re: AC blowng through defrost only
 

yuuuup. We realized we had a problem with the 4x4 hubs in our super duty when we went to put in 4x4 via the dash switch. The AC started blowing out the defrost vents and didn't seem like it engaged. Both vacuum lines to the hubs had broken.

it's a safety thing to default to defrost if no vacuum. Depends on the model Ford as to what year they started using blend doors for vent selection along with temp

Re: AC blowng through defrost only
 

I think on the Mustangs it was 2005, or SN197 body, that blend door control wen to electric motors for actuators. SN is vacuum operated, and I suspect Foxes were the same. I've worked on a number of first generation ones, cable operated. Simpler times.

:borg:

Re: AC blowng through defrost only
 

Foxes were. I had one actuator just behind the radio with a yellow vac in line in my coupe that occasionally worked itself loose. My brothers 98 gt had a broken vacuum line passenger side of the engine compartment. Walked him thru finding it and how to fix it. And the ac is working again for him…