No heat on 2010 T660 with cummins

Right side of the engine. Towards the rear if it is a cummins or a paccar. Right side front if it is a cat.

 

What engine?

 

Yeah, 2 valves directly behind the exhaust manifold. If they are 1\4 turn valves the bar has to be in line with the flow of coolant. If you still have no heat one of your mode actuators on the hvac unit is stuck.

 

You should have two valves, one in the back near the top of the engine and one near the front near the frame rail - the front one will be behind the water pump. You can follow the heater hose to find them.

 

Are you sure?

Check the control valve which is located near the heater core itself, it should be open too. There is no reason why you should not feel the hoses get warm when those valves are open, I burned my hand one of them on a truck when I was trying to figure out if they were open or closed.

 

Right side of the truck, behind the HVAC filter, you'll see some coolant lines running into a device.. black plastic casing with one line running up into the dash, and a curved copper line at the bottom which connects to another coolant line... there'll be an electrical connection into it, as well.. that's your heater control valve, and it's not so uncommon for those to go out.