I have a 2009 4X4, 4.0 XLT. I recently shipped it from Hawaii to Seattle, and upon arriving the truck had no heat. Heater worked fine ( when needed) in Hawaii. Heater control valve works, changed thermostat, and bled coolant system. There is a very slight amount of heat on the vent setting. The engine also surges when holding at 3000 RPM. Put in a 192 thermostat, and gauge sits straight up.