I have a 2008 RRS HSE with a heating problem. The driver side doesn’t get nearly as hot as the passenger side. I’ve been reading all the threads on this topic for months now. Everyone is saying “it’s the heater core!” I’m just having a hard time believing that. In my case if I press the ECON button and the RECURCULATING button it gets warm. But no where near as HOT as the passenger side. I did a back flush of my heater core and found a little debri coming out. But overall clean. For experimental purposes I swapped the direction of coolant flow to my heater core and was getting no heat at all... ?. When the truck is warm, BOTH heater core pipes are hot. So why can’t my half of the vehicle get as hot? Am I missing something???