97 7.3 heater doesnt blow warm
 

I have a 97 7.3 powerstroke. the heat does not get warm! I have no idea why. I flushed the system but prior to that my heat never worked but i was living in california where I didnt need it. now that i am in utah heat would be nice. any ideas would be greatly appreciated!!

The heating system is a fairly simple thing. Water circulates in engine and gets warm. Thermostat opens at temperature and warm water moves into radiator as well as heater hoses into heater core. Blower motor blows over the heater core to radiate heat into cab duct work to heat cab.

Thermostat working ok? Is there one? (Known to be taken out in warmer climates)

Heater core good? Even though you flushed the system.. you may still have a problem with something blocking the tubes or maybe the fins could be damaged preventing air flow?...

I did have a problem with heat not working great at one point. My water pump ended up being bad.. It leaked though. Replaced it and all was well.

Also... are there valves to your heater core? I know on big diesels that tends to be an option to shut off the heat so I am mentioning it.

I actually just figured it out. turns out my entire cooling system (thus the heater as you said) was working perfect. my AC compressor however was intermittently turning itself on and off at 20-30 second intervals thus cooling my supposedly warm air. unplugged the compressor and the heat works fine. no idea what would cause that but I am not to worried about it. wont be needing ac for the next 6 months. then I will just plug it back in

If you had it on defrost the ac is supposed to come on. It dries the air so your defrost works better on rainy days.

thats good to know. and no it was on floor or mix I think. either way at least the heat is warm now. I wonder if the fact my ac works so well was making the defrost colder than normal? i just did the r134 conversion from the old r12 system the beginning of the summer and went from 55 degrees out the vents to 38 degrees. :D:D:D

FYI The only positions the compressor isn't supposed to run is heat, off, and vent...