Based on current product lines, here are features often associated with these Rotenbach models that would appear in their manuals: Rotenbach Portable Air Conditioner (Model 1953)
Is it definitely the , or a different machine (like a generator or lawnmower)? Rotenbach Ersatzteile online kaufen | eBay.de
: This is one of the most comprehensive sources for historical manuals. You can search specifically for "Rotenbach" or "Bedienungsanleitung" to see if a collector has uploaded a scan.