A/C won't blow
 

I am looking for a diagram of the air conditioning system of my 1985 F-250 XLT Lariat. I don't know if this matters, but it has a 351W H.O.

My blower motor is blowing, but I cannot get the vents to open. I don't know if this is the plenum, the vacuum, lines, or a switch. If anyone knows a way for me to troubleshoot this I would greatly appreciate the input. Also, if someone has any drawings, or knows where on the internet I can find some drawings, I would appreciate the information.

Everything you need to know is in this thread: https://www.ford-trucks.com/forums/1...t-working.html

CB - I would rep you if I could. Good job.

RBC - On all but the dealer-installed AC trucks vacuum is used to control the doors of the HVAC system. And dealer-install AC won't have the standard AC vents in the dash, so if you have the vents your system uses vacuum.

The default position for the system without vacuum is Defrost. So if yours is blowing air on the windshield you probably have a vacuum problem. But, I have seen pencils or other things that fall into the defrost vents jam the doors. So check it out and let us know.

E1AZ-19B888-B.. A/C Vacuum Control Selector Valve Assy (Motorcraft YH-380) / Obsolete ~ Dozens available NOS from Ford dealers & obsolete parts vendors.

Applications: 1983/89 F100/350 & Bronco / 1981/89 Crown Vic/Mercury Grand Marquis-all w/factory installed integral A/C.

This valve bolts to the back of the A/C/heater control panel (19980). All the vacuum lines connect to it, then route to the blend door motors (18A318A).

When you slide the lever on the control panel, this valve opens one door, closes another.

Besides this little charmer, one or more of the vacuum controlled blend door motors could be defective.