1999 Ford F-250 Super Duty Q&A
1999 Ford F-250 Super Duty Question: Air Conditioning issue
possible vacuum pump failure.a loss of vacuum will cause air to blow out of defrost vents,and vacuum pumps fail all of the time. - bmdouble
You lost the vacume to the controle unit. It a black or grey vacume line going from the firewall to the intake manifold is where they break most of the time. Check that first. - Your Mobile Technician.com
I recenlty had this happen in my 2001 Cadillac Deville. The A/C wouild only blow through the defrost and floor vents. The cause was a "binding actuator" I took it to the dealer,and the charge was around $495.00. - Visitor
I have a 99 Yukon. It would blow either hot or cold air out of the defrost and floor vents just fine. When switched to blow out the main vents it would sound like it was blowing full blast but only a trickle of air would come out. I heard that sometimes the "blending door"gets stuck. I used the Fonzi-technique and with a rubber mallet (Okay, actually I used my kid's cow flash light that moos every time you turn it on), and beat on the front and driver side of the black plastic box located between the controls and the hump of the floor. (It is the black box that has the center floor vents coming out of it.) It worked and unstuck the door. Now I can switch from defrost to main to floor vents without any problems... - Visitor
I've got some issues with a truck I'm working on. It came into me cutting off when it was warm and you put it it gear. I hooked the computer up to it and it reads P0720 and P0722 when it cuts off I...