What year and camper do you have?
Do you know what model furnace you have? Do you have a heat pump?
Is the cool air coming from the ceiling vents or the vents near or on the floor? The ceiling vents are from the AC system (including the integrated heat pump if you have one). The vents on or near the floor are from the furnace.
Normally the furnace will self shut down if it is not working correctly. Hence, I suspect the cool air is coming from the AC unit.
Can you help clarify were the cold air is coming from
Happy Easter