85 chevy 350 single cab heater/ defrost ?

[true74enduro]

My heater and defroster don't work well at all in my truck and I've flushed my system and changed the thermostat. One day it seemed like my heater got a kick in the jewels cause it got hot. But now today she's just runs the same cold

[true74enduro]

Did these really have this bad of heater

[Keith Seymore]

No - the heaters were quite effective when new (or when functioning properly).

Subscribing to see what the guys have to say about your situation. If you've flushed it (and it's properly filled - no air pockets) then you've done what I would do.

K

[csdineley]

Might try replacing the heater core. Maybe its clogged or something. But my will roast me out.

[Rubble]

Any of my trucks will roast you out @ -30 deg.C . As mentioned before,your heater core could be plugged up.Are both heater hoses hot when engine is up to temp? Also your fan motor might not be moving as much air anymore too.I just changed out the core & fan motor in my crew& made all kinds of difference,also helped when all the mouse nest was cleaned out!!Make sure the air blend door is opening & closing all the way,this will affect it too..

[motornut]

I'd bet with AC?
I'd want to look at the top of the air box,
and by the gas pedal
some of the flaps are vac controlled
can you hear movement with the cables?
does the def/heat selector change the air flow? up/down?

I get lots of heat,but i do run a rad cover ,get heat quicker

[true74enduro]

Yes my truck had ac as well. Thanks guys I'll try the heater core both radiator hoses are hot when engines been run

[true74enduro]

I can hear some movement in cables not a ton.

[nekkidhillbilly]

blend door id say is sticking. yes these old trucks would roast your a$$. my 01 and 04 never heated as good as the squares or even the 88-99 cks.

[motornut]

Originally Posted by true74enduro

I can hear some movement in cables not a ton.

do you get air out the AC vents and heat/defrost at the same time
does changeing the switch make a difference?
if I remember it's only a couple of screws to pull that tube for the dash vents off the front

[true74enduro]

Not a fair difference from
Hot to cold no where normal I mean it's still cold.

[true74enduro]

I'll have to check the defrost vents. I know how to pull the tube off that connects to the heater. After I do that what next?

[motornut]

I was thinking of air "flow" does it move as selected
just undo the bolt you see and you need to push the pin out

[true74enduro]

Now there isn't much change in heat flow at all on the controlls.

[true74enduro]

I noticed today when driving my truck with the heat off I was getting cold air comming in. I dunno if that helps to figure out my problem

[willett]

Are your kick panel vents closed?

[true74enduro]

I felt behind my left kick panel and it was open when I turned my heat on but I didn't check when I was getting cold air

[true74enduro]

Motornut my selector does work as selected slight differences in heat to cold

[motornut]

AC trucks may only have one cowel or foot vent, on the pass side,again controlled
by vacume.if it's not closed it could be coming in there .
could put a manual one in or wire it closed, work back, might find a leak.

[true74enduro]

Ok. As for heat what do you think might help me get the truck hotter?

[motornut]

is that blend door working ok?

[true74enduro]

as far as I can tell it opens shuts

[motornut]

ok
did you remove it and look, or going by sounds like it's moving
I'm asking about the air flow first, not the temp
when you switch the settings of "flow" to the defrost,heater,dash vents
does it change right and stop where it shouldn't be?
the defrost/heater (can be set to leave 1/3 up or down)
more important the dash vents stop flowing,when the def/floor setting goes on
and the def/floor stops when the dash vents are used,try max too(hot or cold)
either way it's sounding like the heater core/air box has to be pulled

[Willie496]

Where is the blend door in my 82 C20?
My A/C is gone (disconnected) and the hot air only goes to the floor not the defrost when I move the lever to defrost. Any help would be great!
Thanks,
Willie

[motornut]

Originally Posted by Willie496

Where is the blend door in my 82 C20?
My A/C is gone (disconnected) and the hot air only goes to the floor not the defrost when I move the lever to defrost. Any help would be great!
Thanks,
Willie

in post 6 are pictures at the blend door