What could go wronge with the heat in a dodge truck

Check your coolant. If coolant is good and no leaks, swap out your thermostat. If issue still persists, it’s more than likely your water pump (it doesn’t have to leak to not work properly)

Do you mean heat up as in does not blow heat in cab or temp gauge does not move?

air lock in cooling system needs flushing with a hose

well that most likely means u blew a gasket dont worry they arent that much most the time if you feel like u wanna try 2 fix it urself i would recamend going on youtube and looking up how to change a theremastat housing gasket. the gasket is most likely 3 to 4 dollars at ur local parts store if not check out local repair shops cant be more han 125.00 by the way if i were u i would change the theremastat while you where in there it bout 15-20 bucks but trust me its worth it

my be the heat sensor indicating wrong reading or you might be having a gasket problem but only if water level is decreasing and/or change into milky or brown color in coolant color

The controls for the a/c vents are vacuum controlled. Check for vac leaks on the engine.

If the pump isn't leaking and you can see water flowing in the radiator with the cap off, the pump is probably OK. Can you figure out where the coolant leaked out?

Get your oil leak fixed the more oil you leak the harder the engine has to work thats why your burning alot more gas

Remove the hood bracket bar, 4bolts, then the fan shroud assembly, then the belts, belt adjuster, and timing covers, line up the cam gears, crank gear to the marks , cam has 1 dot, they line up to timing housing 2 dots, (single dot to middle of the 2 dots), crank has 1 dot to mark on the oil pump housing to your right of crank gear, thats TDC. now remove the timing belt tensioner, 2 bolts, and remove the belt, if the pump has leaked, replace the belt, and tensioner if it is NOT metal Pulley, the fibre one will break down from the antifreeze. its a good idea to replace the water pump housing orings behind it, ac bracket has to come off, as the right cam on engine, this not a retiming iussue with the gear. GOOD LUCK. RDJRP

Did you have your heater running when you refilled coolant after water pump changed?