On my '04, The exterior temp sensor usually reads 4* higher than normal where as on my '15 wrecker, its spot on. Could this be the sensor and is it the same as the mid-90's panther cars? And whether I'm at high idle engagement or low idle, It still takes this truck 10 minutes to warm up in 40-ish degree weather. And when it finally does, my heater lines feel hot but the air coming out isn't until about 5 minutes later. I also have a loud rushing sound behind the dash and in the cowl. Air flow isnt that strong either. Its acting like it has a blocked cab air filter which it doesn't have and a clogged heater core but both lines are hot. Anyone have a troubleshooting chart I can go by for the hvac system? Coolant cap is still factory original. But, I'm not loosing any coolant. And if so, Not enough to really notice.