A/C Help

[nacy369]

When i start my truck and put it on vents, flip it too max a/c it works till the truck warms up then it blows out hot air out the defrost. Even blower off still blows out the defrost, nothing comes out the vents no matter what setting. Any ideas? Btw its a 1998 B4000 4.0L

 

[TomJenks]

sounds like a broken blend door. Or the actuator has went bad.

 

[Earl43P]

You need to look at the vacuum tubing to and from the accumulator (that black plastic sphere on the DS fender liner). Default position is Defrost, so if it isn't getting any engine vacuum, that's where to start looking. The rubber nipples where the tubing enters that sphere, holes burnt/rubbed in the tube, etc.

You could also pop the glovebox all the way past open and look at the actuator, but blend door problems usually default to Hot.