Dash HVAC replacement or repair?

[OnTheMove]

A year ago my dash heating and a/c system started acting up. It didn't get very cool or very warm. I checked all the normal vacum problems. Everything seemed to be working properly. Then all at once it wouldn't cool or heat at all. After checking out the system under the hood I found the casing cracked and shadered and it was falling apart. Air was infiltrating from outside into the box and mixing with the cooled or heated air. I'm not sure but I believe the mixer door inside the units is not working properly.

The question is does anyone out there have experience with replacement or repair of these units? My coach is a Winnebago 32' Class A on a Ford chassis (2002).

[OnTheMove]

A year ago my dash heating and a/c system started acting up. It didn't get very cool or very warm. I checked all the normal vacum problems. Everything seemed to be working properly. Then all at once it wouldn't cool or heat at all. After checking out the system under the hood I found the casing cracked and shadered and it was falling apart. Air was infiltrating from outside into the box and mixing with the cooled or heated air. I'm not sure but I believe the mixer door inside the units is not working properly.

The question is does anyone out there have experience with replacement or repair of these units? My coach is a Winnebago 32' Class A on a Ford chassis (2002).