Per advice from this forum, I called my extended service plan provider for help in resolving my faulty dash A/C. They were willing to step up, BUT only after I confirmed with Freightliner that the problem was/wasn't covered by the chassis warranty. Freightliner explained that their responsibility for dash A/C began and ended with the compressor. To make a long story short, the compressor was the root problem, and Freightliner is repairing it under warranty. I'm scheduled to pick up the MH tomorrow morning.