I have a 2003 Dodge ram 1500, 4x4,5.7. I've replaced the thermostat and am not getting any heat out of heater. When engine temp is at normal operating temp and you turn the fan on and turn the knob to heat it gets hot for a couple of seconds, then blows c

sounds like a plugged heater core, are both heater core hoses getting very hot and the same temp on both hoses?

you can connect a garden hose to the core and check flow. remove both hoses and connect a garden hose to one core fitting.
the flow should be the same as the hose flow by itself.
if a lot of shi# comes out while you are testing it, reverse the hose on to the other fitting on the core and flust it, you might have solved your problem right there.
if not let me know and we'll take it to the next step.
mws919

check the coolant level (low coolant can cause this). If the level is low have the system checked for leaks.

I checked the heater hoses at operating temp and they were both roughly the same temp. I got home from work and flushed the heater core with a garden hose and holy shi#! You could fry an egg now! Thanks for all the input it was greatly appreciated!!!!!

i'm glad i could help, need any thing eles, i'm here.
mws919