My heat will not work the truck heats up to 190 but i have no heat inside? The blower still works and it also still changes the vents when i turn the ****. I get a little bit of heat when the **** is on low but once i turn it up nothing? I put a hose to the heater core water comes out fine? i even changed the heater control in the dash with one that a buddy had but still nothing? Thanks Rich

There should be a flapper somewhere in the heater to let air come in from part of the box where the heater core is,I'm betting the actuator there is not working,cause' of a vacuum hose,or bad diaphragm.
I've never had that problem,and I don't know where my darn book is,but that should be the problem.

hey man, mine does the exact same thing. if ya get yours fixed before i do let me know what it was. ill do the same.

If you do a search for heater here in the cummins section another guy had this same problem within the last month or so and his post should be in here someplace.

Nevermind, that post was Biged himself. Guess you never got it fixed eh.

If you have hot coolant getting through the heater core it almost has to be the flapper door not moving right cutting the supply of cold air off and it's vacuum operated.

Sound like the blend door is stuck... It not vacuum driven... Its got a stepper motor that moves the door. So check the rheostat (control), check the wiring, and the last step is the blend door...(Might require removal of the HVAC system to fix it...)

I've got a write up on diagnostics...
Heater

Before performing the following tests, refer to Cooling for the procedures to check the engine coolant level and flow, engine coolant reserve/recovery system operation, accessory drive belt condition and tension, radiator air flow and the fan drive operation. Also be certain that the accessory vacuum supply line is connected at the engine vacuum source.
Maximum Heater Output

Engine coolant is delivered to the heater core through two heater hoses. With the engine idling at normal operating temperature, set the temperature control **** in the full hot position, the mode control switch **** in the floor position, and the blower motor switch **** in the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the HVAC housing floor outlets. Compare the test thermometer reading to the Temperature Reference chart
Obstructed Coolant Flow

• Faulty water pump.
• Faulty thermostat.
• Pinched or kinked heater hoses.
• Improper heater hose routing.
• Plugged heater hoses or supply and return ports at the cooling system connections.
• A plugged heater core.

Mechanical Problems

• An obstructed cowl air intake.
• Obstructed heater system outlets.
• A faulty, obstructed or improperly installed blend door.
• A faulty blower system.
• A faulty a/c heater control.

hey, my blend door is good. ive taken the electric actuator off the bottom and you can turn it by hand. you can here it when it hits one side, then when it tuns and hits the other.
when i first turn it on vent it is hot for about one second. then it goes to cool. not cold but right there on the verge of being cold.
i got two buddies who work at a dodge dealer.
1. one of them told me it might be a plastic bag got sucked up somehow and is blocking the heater core, but in my thinking if it is blocking the heater core, how can air get past it to blow out the vents.
2. the other said i might have only one tube flowing coolant through it. the rest are plugged up. thats y i can get water to go through it but still no hot air.
what do yall think about these two guesstimations?

I think #1 is more likely than #2.
I hear it's a real bitch to get the heater core out...

ive already pulled the dash once for this reason. well to fix it from only blowing on the feet. should have changed the heater core while i had it out, but the guy helping me talked me out of it.

DOH!

i hate listening to other people. first a plasma cutter ordeal then a dash or deal. what next, i hope nothing.

If its plugged up you will have to pull it out...

All this could of been prevented by just changing you coolant at every 30K miles as suggested... My coolant system looks factory fresh after 6 years and 137K miles.



No lime scale here or rust in my block...

Just because the coolant is green DOES NOT mean it still good... This where everyone make this mistake and heater core & radiator fail (leak or plug up)....

mine probably was never changed. idk cause i bought it with 125,000 on the clock. had a cracked block when i bought it. i know it has had stop leak in the radiator. they left6 the can under the hood when they put it in. should have sent the truck back then.