85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

Did these really have this bad of heater

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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..

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

I can hear some movement in cables not a ton.

Re: 85 chevy 350 single cab heater/ defrost ?
 

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.

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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?

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

Are your kick panel vents closed?

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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.

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

is that blend door working ok?

Re: 85 chevy 350 single cab heater/ defrost ?
 

as far as I can tell it opens shuts

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

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

Re: 85 chevy 350 single cab heater/ defrost ?
 

in post 6 are pictures at the blend door