94 Chevy Suburban heat not getting hot?

[C live]

I have a 94 Chevy Suburban my heat won't get hot warm but not hot what would cause this problem flushed radiator, also no leaks

 

[Eric F]

ok, you flushed the radiator.. did you change the thermostat? it could be stuck open or partially open from the flush. the gook could've lodged in the opening..
otherwise, could be your antifreeze/water mixture is to concentrated..

 

[Charlie]

Could be thermostat going bad or just the temp there, is your guage running the same for coolant temp? If really cold you could block off lower 1/3 of your radiator to help, just keep an eye on the temp. Also check to see if the clutch in the fan is not bound up. When cold (like before starting in the morning) pop the hood and spin fan blade by hand (not belt). Should turn fairly easily.