At 20,000 miles we could smell a hot coolant odor inside the cab of our 2016 Ram 2500 Truck, dealership topped off fluids, but odor strong when turning on heat. At 35,000 miles same issue and dealership added orange coolant again. Now at 50,000 miles shampooing carpet and front passenger side white foam turned orange. Eureka! I think I discovered a leak in the coolant. Hoses laying on engine under hood, but intact and suspect a bad heater core. Took the truck in and was charged for a new heater core to replace it. Not very happy!
Heater core leaks are usually obvious. But at least it is fixed now.