2008 1500 5.7....not enough heat coming through??

[Imncrxtc]

Hi guys, i have a 2008 1500 sport. Its not generating enough heat inside the truck. I have changed 2 thermostats, thinking one was bad out of the box, and there is no change. Where else can i start looking to for the culprit?

 

[Fast69Mopar]

Hi guys, i have a 2008 1500 sport. Its not generating enough heat inside the truck. I have changed 2 thermostats, thinking one was bad out of the box, and there is no change. Where else can i start looking to for the culprit?

I am guessing you have checked the coolant level after replacing the thermostat. The next thing I would do is get the truck running and up to normal operating temp. Turn the blower on and set the temp to the full HOT position. Open the hood and feel the heater hoses at the heater core and see if they are really close to the same temperature. Also, feel the upper radiator hose and the lower radiator hose and see if they feel close to the same temps. If you can get your hands on an infrared temp gun that would be best.

If they are close to the same temp then we can assume we have normal coolant flow through the heater core. If the temps are different between the inlet and the outlet then suspect an obstruction in the heater core.

Another thing you can do is to monitor the blend door actuator while rotating the temp control knob on the HVAC Control Head and see if the actuator is moving without any restrictions. You can also remove the blend door actuator and operate the blend door by hand to see if it moves correctly.

 

[Imncrxtc]

Thank you.
How do i check the blend door actuator?
Also i do notice that the temp on the lines going in the rad is hot. But the line going out is a little cooler. There is a difference for sure. I couldn't keep my hand on the hose going in for how hot it was. But on the line going out, i could.

 

[Bloody_Knuckles]

The only way to see if the blend door is moving is to actually look at it while you are operating it. Unfortunately, that is nearly impossible. But 9 times out of ten if the hot water is circulating and the heater core isn't clogged with dust and dirt, it's the bland door. Buy a whole set of doors so that when you take it apart, you can see if the others are broken, too and replace them while you have it apart. Takes about 6-8 hours.