My air still blows cold, but today (heat index 105) all the air only comes from the Defrost/Floor mode. Air blowing is cold. It will switch to Off. But it won't change to use the regular vents.

Anyone got a fix?

 

Vacuum leak. Check under the hood where the vacuum line for the HVAC controls comes into the cab. The plastic lines tend to get brittle with age, and break.

 

Also the plungers for the blend doors can start leaking with age. If you don't find a vacuum leak in the bay side then your going to have to pull the dash. While your in there it would be a good idea to consider replacing the heater core and ac condenser. Its a really long job not for the faint of heart.

 

Thanks for the help guys!!!! It was definitely a vacuum issue. Easiest fix I've ever done on this truck. Attaching the vacuum diagram, and my before and after pics for anyone else that needs them.

 

I would get a rubber T fitting from a parts store. That tape will dry and get dusty right when you need the heat/AC the most. XD

 

Either that, or just a short piece of appropriately sized vacuum line to use as a splice.