Getting to be that time of year where I need the heater. I cant' seem to figure out what's going on with mine. I can turn the blower on and get air, but it's cold. Both heater hoses are hot, indicating water is getting through the core. Must be the heater box. When I move the air temp selection slider to "hot" I can feel resistance like the flap is still connected inside the hvac box, but I still can't seem to get any heat from the vents. Same goes for defrost and floor. Any ideas, boys? What's the easiest way to remove the hvac box or to manually turn the flap to the heat side?

 

Some people have experienced a blend door that malfunctions up in the duct. I have never had this problem, but maybe you can search "blend door" and find some info on it.

 

Assuming you don't have AC, you can remove the glove box and have pretty ready access
to the cables & levers.

I recently reinstalled my heater core (non-AC) and glued new foam rubber to the pieces that
had the factory stuff, the original foam was dry-rotted and turned to dust by merely touching
it. I'm hoping this will reduce the amount of warm/hot air that seems to leak past the blend
door Franklin mentioned and help make it a bit cooler in the summertime.

IMHO it helps a lot if the dash pad is removed if you're gonna remove the heater box.

Are you sure you don't have some sort of inline coolant shut-off valve on a heater hose?
Some vehicles with AC have those.

 

Thanks for the replies, guys.

Truck does have AC (non working). No inline shut off valve. I am going to fiddle with it tomorrow. I'll report my findings.

 

This may seem silly but it does happen to over look the obvious. Is there coolant in it? Hoses and stuff would still get hot but no heat from heater.

 

If you have AC, your controls are all vacuum-operated; are all your under-hood vacuum
lines connected? Don't know much about the AC-equipped variants, sorry.