Heater is not working. Help Please
 

Ok, so the heaters worked before i did this install, i bought a sinister coolant filter kit. once i installed the kit the heater stops working. i installed this on two trucks today same problem on both. idk if i cut on the wrong hose but im pretty sure i didnt. on one truck when i cut the hose on the passeneger side no coolant leaked out so i didnt add any more.. on the other it leaked a bunch and i added more. so the coolant on both trucks are good. any idea?

check the small hose that attaches to the heater valve in that same line, it gets knocked off all the time when working on the pass side of motor, it is right near the oil fill spout.

If your talking about the grey vacuum line that attaches to the thing on the coolant hose then yes there is both plug in on both trucks. ??

Ok, i found what the problem was. As i was looking behind the glove back to make sure all the parts were moving. including the thing people call the flapper or the door, seeing if i could hear the change of air to heat and all it was good. i then decided to make sure all the hoses were connected tight after doing the coolant filter kit and all was good, double checked coolant and it was good. finally after all that it turns out to be a thing of wires stopping the plunger thing from moving in and out of i guess you called it the heater valve.

so in the first picture shows the wires behind the valve stopping it and in the 2nd photo shows how i fixed the problem. right when i moved the wires the heat comes back and problem solved.

so i hope if anyone is having heating problems and did all those things and could find what it was just make sure the thing of wires isnt blocking the valve and a simple zip tie will fix it.

That is actually the MAP sensor hose, I goes from the MAP sensor to the intake manifold. that hose often gets left off when people remove the intake to do oil coolers or EGR deletes then they have sluggish running and not showing any boost on gauges. Good find and glad it was something simple, thanks for sharing what you found, often times the simple things get overlooked.