I need help, I gave the truck a new air filter and put it all back together and now I dont have any heat. I flushed the radiator out and topped it off with 50/50 and the damn thing just will not get hot. The inlet hose is hot and the out let is cooler then the inlet that is running through the heater core so that all seems good, but still no heat. If you have the fan on high it blows cold air like it was low on antifreeze, if you leave it on low it blows some heat. any ideas dodge boys.
Mark

the heater core could have air in it take off one of the heater hoses to see if it is going through if not take off both hoses and run water through the heater core both ways that should do it if not move to florida

A number of things could be happening. The thermostat could be stuck open. I've replaced these before only to have no improvement. It turned out that even the replacement thermostat was defective. On some cars it's easy to reverse the thermostate, so make sure it goes in the right way. I also had a car once where the cable that operated the air door bent and wouldn't open the door. There should also be a control valve that regulates the amount of water that passes through the heater core. Check to see if this valve is working correctly.

The truck runs steady at 200 degrees, so I think the t stat is ok, I will check the for air in the core, and for the door to be open and closing along with the control valve. where the hell is this valve? Thanks for the help guys, the wife might not be happy once it gets cold, something about cold leather on the ass does not do much for her.
Snglestack I like the idea about Florida

Sounds like a heater core problem, and for your sanity's sake, I hope you do not have to replace the damn thing. I have replaced two on GMs and they suck big time to get to. If you want someone else to do it, its $50 parts and $400-$500 labor. When you are flushing it, be gentle, so if it is clogged, or has air in it, you will just ease it out, and not rupture it. If you rupture it, you have a definate replace now situation.

brian good advice they are a project to replace

The core could be clogged too.

Check vacume lines under hood, you might have knocked one off to the heater control valve or to the vacume res. wich operates the vacume doors inside the truck