2003 Adventurer Dash A/C

[navychaps]

Has anyone dug into their dash to get at the mixing box? Dealer just quoted me $3200 to diagnose.

[tderonne]

What do you mean by mixing box? Where the heater core and AC evaporator are?

It's underhood. Some folks have removed the front cap to change the heater core. I've changed one in a '99 Adventurer without pulling the cap.

If you mean the distribution box (my name) that the hoses from the various vents connect, that's right in the middle, inside. Whole dash has to come out to get at it. I've done that too, in my '04. Not easy.

[Ray,IN]

Describe why you think the mixing box needs replacing. If you are getting hot/warm air mixed onto chilled air, consider simply installing a on/off valve in the heater hose coming from the engine. You won't forget to turn it back on come winter, you'll miss the heated air.

[navychaps]

Thanks all. My air will not switch between defrost, dash and floor.

[Old Scout]

….that is a whole different issue--sounds like a vacuum line leak.....

[tderonne]

Right, seems like a different issue. $3200 to diagnose? We work for free around here, wish we could charge those rates!

This post might help:
Heater/AC stuck on defrost

[Skip426]

Defrost is the default for your dash A/C system , lack of vacuum the system goes to default .
Your issue can be as simple as a cut/disconnected vacuum line .

MANY posts an this issue.
Any shop that quoted more than an hour to diagnose , is a shop to avoid.
Either they have no idea what they're doing , or just want to take your money.

EDIT: Here's another thread with pictures that may help . NOTE the only difference between your coach system and that on a diesel powered coach , is that the gas powered coach uses intake manifold vacuum and the diesel coach requires the vacuum pump to operate the system.

http://www.irv2.com/forums/f258/dash...ch-490445.html

[Duner]

On my 04 Winnie, the problem I had was a/c blowing out the heat ducts by my feet. I fixed it by replacing the plastic vacuum line in the engine compartment that was damaged from the engine heat.
My bet is your problem is also a damaged vacuum line.
Good luck,
Bill

[navychaps]

Vacuum line pressure test is good, so it has to be something more...

[tderonne]

So the vacuum lines are “good”. It doesn’t switch. What is it stuck doing?

[Skip426]

Originally Posted by navychaps

Vacuum line pressure test is good, so it has to be something more...

If you have vacuum to the control head and the unit is still stuck in default ( defrost ) then testing of the control head vacuum to the various actuators is the next step .

BTW: I've seen the vacuum control heads plug up and not distribute vacuum so not totally unusual.

With this vacuum diagram you can test the control head distribution of vacuum to the various actuators. Some crawling around under the dash is required .
With the control head , set in a position ( by the tube color ) identify the actuator ; remove the tube ;and check for vacuum there.
Usually the recirc actuator is easiest to get to , on the outside of the firewall , so if you have vacuum at the control and none to the recirc actuator then your 99% sure you need the control , but continue testing at the rest of the actuators to be sure.

Recirc actuator ( blue vacuum tube )will look like the second picture.

[navychaps]

Originally Posted by tderonne

So the vacuum lines are “good”. It doesn’t switch. What is it stuck doing?

It stays between Defrost and dash

[Isaac-1]

How did you pressure test the vacuum lines?

[navychaps]

Originally Posted by Isaac-1

How did you pressure test the vacuum lines?

Dealer did it for me.