ChrisLib

There is also a duct,located under the dash, about centered in the middle, this duct route`s the air from the heater box up into the plenum/air mix box where all the doors are for heat/def/vent etc. This duct was leaking a good bit of air on my 86. You can get it out with out taking the whole dash apart, I simply removed it, scraped off the old disintegrating foam and put some stuff i got from home Depot (about 1/2 in wide sticky backed stuff). Might want to ck that out as well while yer under there. I HAD pics but can`t find them

hippie

When I clean the heater box I use a fine brush with stiff enough bristles to sweep out the fins and vacuum it out also. You may check and see if the heater core might be pluged up. Just a thought. I don't have any problems with mine in cold weather. I haven't had to use a winter front, yet... =You may want to have your radiator rodded out and flush out the heater core too. I change my antifreeze every year and I mix it 60/40 with distilled water, and every other year when I change out the antifreeze I change all of the hoses. Of course I'm on the road all of the time. Just something to think about...

andyr354

I looked through the inside air intake like sugested, looks clean as can be in there. Just some tiny pieces of fuzz is all.

I might swap in a different fan motor as I cant feel any air leaking around the defroster duct either. Measured 10.5V on high at the fan motor on high with the engine off, could be alittle higher, but that is not all that low.

I might ditch the vacumm actuated collant valve and go with a manual gate valve to see if I can get better flow.

hippie

Hummm, Something has to be blocking the air flow I would think, or it's being deverted. What is the voltage with the engine running?

andyr354

I can see up through the heater vent on the drivers side that the flap is swinging over and directing air up to the defrosters ok. There could be some junk in the duct I guess, But dont see how I could get it out unless I pull the cap off the dash.
I could maybe take the floor duct off and look up from the bottom side with a mirror or something.l

I get a good amount of air out of the heater.

hippie

have you pulled the fan out to see if it's clogged up. I wash out the cowl in take just below the windshild. I try to watch where it drains from to see how much drains to see if it's stopped up. I try everything I can to wash it out because where I am sometimes has a lot of leaves falling. There is a door in the air box that's on the right side ( passenger ) check up in there. My truck pumps the air out all of the vents and I have no problem with the lack of air.. That's has me woundering