https://www.rvtechlibrary.com/heatair/RVP_tstat_install.pdfClick for your manual and troubleshooting.
2011 Phaeton. Front and Rear can be Heat Pumps or just AC. OR can be 3 Heat Pumps. 2011 Phaeton, will assume you have LP furnace(2). Front and Rear. Phaeton with 3 roof top units, only have 2 Furnace zones. Front and Rear. NO middle furnace or Heat Zone. UNLESS your middle Roof top unit is a Heat Pump. Which will only Heat the "middle" if on Heat Pump for heat. IF you have an Aqua Hot, same for Heat thru floor. ONLY front Zone 1 and rear Zone 2 are connected to the Aqua Hot furnace system. NO middle. If your unit still has the Model and serial numbers of the appliances on the wall in rear bedroom, you can see if all 3 AC units have the same Model number. If you still have that post the model numbers if you have 2 different model numbers. Doug