Heat bleed through

[79bonanza]

Hey guys, my 91 k5 has prolly the same heat issue every square has that I've been around. My heat bleeds through the vents while driving. Normally it wouldn't bother me but it's been in the 90's here the past week and it's getting pretty hot.

So does anyone know how to keep the heat from leaking thru the vents into the cab.

I don't wanna completely cut out the heater core coolant circulation either, I've seen that done before. Not my style I guess

 

[tRustyK5]

Probably the blend door tab is broken. Search here for "blend door" or "blend door tab" and some good stuff should come up.

 

[handloader90]

I would just take the fuse out.

 

[79bonanza]

Okay yea I've heard about trouble with the blend air door tab.

And the blower isn't still running so pulling the fuse wouldn't do much

 

[diesel4me]

You could pinch one heater hose shut with a c-clamp or vise grips and two blocks of wood--or use a ball valve and two barb fittings.......GM used vaccum controlled hot water valves on A/C equipped vehicles so the heater core wouldn't be "fighting" the A/C evaporator core ...