Ok so I was riding with the ol' lady's dad yesterday in his 1999 2500 with the 5.9, He said hey check this out. And he reaches over and turns the Air Conditioning. And out comes the heat full blast???? I'm like WTF? Hes like yea i know. He said the cable in the dash is messed up. I didn't know we had a control cable to control the climate control. So I thought I would look on the forum and the search has left me empty handed. So anybody have any ideas the cause to why the air conditioning is the heat and the heat is the air conditioning?

 

How cold was it out?

There are no cables behind the dash. Only vaccum lines.

 

Thats what I thought but he said there was a cable connecting the heater to the ac and its out of adjustment. I think he's full of it but w/e. As far as the temp goes it was around 30* outside. truck was warm. Just strange on the controls.

 

The only two things that control behind the dash are vaccum acuators and electric motors.

 

if you turn the selector to MAX AC, and rotate the temp dial to hot, it will blow hot air. is that what your talking about ?

 

Nope. Turn it to cold and max A/C and you get heat. The other Way is the A/C. So the only thing that came to mind was that the lines are backwards. But how on earth could that happen without pulling the dash and flipping the lines?

 

Does it do that in the summmer too?

His blend-air door may be messed up.

 

Dunno about the summer we don't use the air that much. So this blend air door is a vacuum operated door that switches between the heater core and the A/C?

 

Its an electric motor that operates a door that moves air through the heater core or the a/c evaporator.

 

Ahhhhh ok. So I wonder how hard that would be to replace if it is bad? I still wish I knew how it could get backwards if its a motor??