Many RV manufacturers use Evan Tempcon HVAC controls.
Evans Tempcon, Inc
You might check with them and see if you see a matching control panel. If it is a GM control, I'd suggest a salvage yard for a replacement part.
First, you might check for vacuum. The vent motors all work on vacuum. If vacuum fails, the vents default to the defrost vents. If that's the only place air comes out, I'd suspect vacuum. If it's a diesel, it has a electric vacuum pump probably in front of the windshield. With ignition on, you should hear the pump.