Sorry to be posting ANOTHER heater problem, but couldn't find a post with my same symptoms.
Bought a 99 Ram 2500 5.9 little over a year ago to haul my horse trailer. No problems with heat last winter, darn near ran me out of the truck!! Temp gauge has always run @ 210, summer & winter.
Drove 45mi to work the other night, (20 deg outside) Drove 30 mi before I could hold the wheel w/o gloves on, never did really warm up. Temp gauge about 170. Lukewarm air out of vents. Called hubby told him I needed a thermostat.
Next am (10 deg) Checked radiator, topped off with VERY small amt of antifreeze, added some to reservoir. Noted small amt of scum on inside of rad. cap. also with truck running it didn't look like the fluid was circulating.
Put a LARGE piece of cardboard in front of radiator, no help whatsoever.
OK, he change thermostat but it didn't help. Next we changed water pump, flushed the system, back flushed the heater core, filled with new antifreeze. still doesn't look like it's circulating. Still runs cold, 56 deg. out & cardboard still in place. No heat.
Someone posted somewhere it could be a head gasket. Would that make an engine run cold?? I just checked the oil & it looks fine.
BTW about a month ago I was hauling home when my check engine light came on. I first thought it was bad gas. I normally gas up at the same station. The next time I drove to town I stopped at a National parts chain to use their scan tool. It didn't pull up any codes, figure it was a bum scanner but haven't tried another. ANY suggestions? Please?
Thanks in advance.