heater help!

[beaterheep]

so, why the hell does my heat blow decently hot from defrost, but when i put it on heat it blows barely any warmth? truck can run for hours, defrost is warm but not hot, and heat is barely what youd call "room temperature" it friggen sucks!! any ideas?

[89flat]

have you done any bumper mods in the front?if so the vacuum canister there is the heater control canister just like the vacuum operated 4x4

[64 Cheyenne]

have you done any bumper mods in the front?if so the vacuum canister there is the heater control canister just like the vacuum operated 4x4

 

Meaning did you cause a vacuum leak that affects heater door operation?

 

I also have heater issues (low output temp).

 

Today I'm going to flush the cooling system and try to back flush the heater core.

 

Did this last weekend to the GFs XJ, it helped but still wasn't what was expected in terms of heater output.

 

Outside temps were around 0* so I kind of have to take that in to account, my best guess is clogged heater

 

cores on my MJ and the GFs XJ.

[mnkyboy]

Mine is pretty weak as well. It doesn't make sense my xj will try to cook you and my mj does its best just to defrost the windshield,I would think the opposite since the xj is heating alot more space.

[beaterheep]

ive got an arb bumper but the vac can is still there. thinking ill ditch the stupid valve on the heater hose under the hood and see what that does. should help a little, then if need be ill unhook the heater door and just move it manually to hot for now lol