R Walter

Went to switch on my AC in truck no 1 in my signature today, and was not able to get any cold air through the in-dash vents. It seemed to be making cold air fine because I could feel nice cold air coming through the two floor vents normally used for heat. Every time I switched to the in-dash vents... nothing.

Any ideas what's up?

torquefan

It's possible the vacuum actuator for one of the mode doors in your HVAC system has stopped working. You can leak test them with a vacuum pump, and sometimes a visual inspection is all they need. I've seen a few with the diaphragm all swelled up from a bit of oil intrusion over the years.

I'm guessing it isn't a vacuum supply problem, because with no vacuum the system should default to defrost. I've never seen a broken door on a 2nd gen, so unless a foreign object has found its way into the system and jammed a door open, (fairly common-pens down the defrost vents) my bet is an actuator.