Heater blowing cold coolant seems to be not circulating

Hi,

When the engine is at operating temp and the heater is on high, feel both heater core hoses. Are they hot? As far as the hoses, as long as water is flowing through the heater core, it will heat. I attached a pic showing the supply and return hosed on the engine. I have nothing for the core.

As far as the radiator cap, are you sure it is good? It may not be holding pressure.

Let me know if the hoses to the core get hot. If they aren't, specifically the supply hose, something is blocking coolant from circulating through the core. If the vehicle is running at proper operating temperature, then it's getting warm enough to heat.

Let me know.

Joe

Thanks for the reply back. The supply hose is hot but the return is barely warm. Suspected the heater core was stopped up. I flushed out the core and had heat for about 30 minutes. then it went cold again. I flushed both directions and had a good stream both ways. Do you think it stopped back up? Does it matter on the core which hose connects where ? Does it have an in and out ?

Hi,

It may have plugged again. If the return is not hot, it isn't flowing through. As far as the hoses, it really shouldn't matter. Usually one is slightly larger than the other, but I can't remember if that is the case with this truck. It wouldn't hurt to switch them to see if it makes a difference. However, if you had heat for 30 minutes and then it stopped again, I suspect hoses aren't the issue but rather the heater core is plugged again.

Let me know what you find.