I have a 2001 super crew 5.4l that blows only warm heat. The control **** on the dash and blend door are working properly. I changed the thermostat,the radiator cap,flushed and back flushed the heater core( no deposits came out - only clean fluid) the radiator is new (blew only warm heat before rad. replacement) The engine temp is normal and both heater hoses are warm to the touch, but not hot. Any ideas? Thanks, Rich

 

In mine the ac compressor cuts on on every setting but just panel so if I want it to be hot have to run in on just that

 

Mine does the exact same thing!! I have no clue what the hell the problem is.

 

Still sounds like a heater core issue, undo your heater lines again and let some clr sit in there for a few hours, flushing water through alone won't unclogged the caked on crap inside the core.

 

Me either man gotta be vacuum related I guess if you figure it out PM me

OP I also had to flush mine did it for like ten minutes, just the heater core, and after like 8 minutes a bunch of crap came out, how long did you flush yours for

 

I didn't flush it for very long. If the weather is nice this weekend I'll try again. I'll keep you updated. Thanks everyone for the advice

 

I tried the CLR and flushed it again but no difference. I think I'll wait until the weather gets better to work on it anymore.

 

Did you try running it only on panel

 

Check to see if your blend doors are working properly. Just cuz the switches move nicely doesnt mean the doors are. Could be blend door motor, linkage came off, blend door jamming on something, vacuum line disconnected etc.

 

Yeah, I tried panel - no difference. My first thought was blend door. I cut the heater box open and the blend door is working properly.