2004 astro van when turning on the ac the air comes out defrost.

they damper door is stuck could be on the dash control or the damper door itself

The mode doors in the dash are powered by engine vacuum, if vacuum is missing the default setting is the defrost vent. Look under the hood near the firewall for a disconnected vacuum line.

hello, ac freon is 5.00 can, accum run from 20.00 150.00 depends on what veichel it is, ac oil, couple dollars, most of the time ac clutches dont go out that much, usually when the clutches go you get another comp, or rebuild yours, comp, arent that expensive for the 2000 astro, probably couple hundred dollars, with a core charge, sounds pretty high to me depends on where you live too, , different prices,

If it is blowing hot air out of the defroster and not out of the heater vents then the door that directs the heat from the defroster isn't working properly it is blocking the heat from going to the heater vents. Also check the cold air door. It sounds like it isn't closing all the way to shut off the cold air and not letting the hot air pass.

when you turn on ac look for front ac clucth to be turning. if it is feel the lines up to the cowl if they are cold 40 degrees or so theres probably enough charge with the year of that vehicle it maybe low on charge ac systems will usally hold for at least 5 years.

SOUNDS LIKE THE AC CONTROL HAS LOST VACUUM FROM THE ENGINE, YOU MAY HAVE KNOCKED A HOSE OFF WHILE CHANGING THE FAN CLUTCH, IS THE AIR COMING OUT THE DEFROST VENTS BY CHANCE?

Most likely the small vacuum hose under the hood broke just under the rudder air intake near the throttle cable bracket.

when your on defrost the ac will automatically turn on if its not on defrost the ac shouldn't come on thanks

i suspect the vents are controlled by vacuum and are not opening due to a vacuum leak.

Robert

Replace the broken vacuum line that runs across the top front of the engine.