Yep....mine goes to Fast Idle when ever I'm in neutral and the A/C is on. When you have the A/C on, the engine fan goes to HIGH and stays there, consequently causing the fast idle to come on. If you can remember, especially in a campground with dirt roads, turn the A/C off while moving the coach to your site. This turns the fan off of HIGH and you'll stay cleaner and the neighbors will appreciate it too!
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor