Roof a/c froze into a block of ice overnight.

Are your controls ON the unit itself, an just a couple knobs, one for Lo-Hi Fan then Lo-Hi Cool, the other for Temperature? If so, there's no "freeze sensor" like the A/C's that are ducted and have a wall thermostat have. We've had two Class C's, both withe non-ducted A/C's with two control knobs. They'll freeze on the Low Fan setting. They're also much more likely to freeze if the condenser coil is dirty. Warm air passes into the A/C by way of the Filters, then through the condenser where it's chilled (and humidity condenses out as water) and then the air blows back into your coach. So... Dirty Filters, Dirty Condenser, Low Fan... all contribute to freezing like you just had. Chris Bryant has a thread on how to clean the A/C's coils. You have to go on the roof, remove the plastic shroud, then remove part of the sheet metal air box over the condenser. Not hard if you're comfortable climbing onto the roof, using a few simple tools, and doing some cleaning. Power has to be off, and you need to be careful not to flood the inside of the coach with water coming down form where you saw the ice.