Heat pump blowing cold air

This IS NOT an Aqua Hot. The bus uses a Webasto system (50,000 BTU) for baseboard heat. It keeps us toasty warm in Temps well below zero. We have NO 120V heat other than the heat pumps and heat straps in the roof A/C units. Most Prevosts have basement air units called Cruiseairs and not roof mounted units. The newer ones are all going to roof air due to the PIA issues of the Cruiseairs. The bus is very air tight and we just use a couple portable heaters for most of the Winter. When it gets cold enough to be concerned about the bays getting to cold we turn on the diesel heat. Since we carry 160 gallons of fuel it will keep us warm for a Very long time.