How much defroster air?
 

After working on replacing my defroster actuator today I decided to keep the original actuator because I found a small piece of cracked vacuum hose leading to the actuator which I think caused the defroster door to malfunction (and the replacement "one size fits all" actuator would require significant modification.)

I now have the door functioning properly, but I don't seem to have very much air coming out of the defroster vents. The air blows fine out the floor vent when the control is set to HEAT, and when I set the control to DEF the air to the floor is very much reduced, and the air flows out of the defroster vents - just not very strong.

I seem to recall that my old 73 C20 454 (no A/C) had a lot stronger flow of air out of the defroster. This truck is an 83 C20 454 with A/C. Do you guys have a flow of air out of your defroster vents as strong as the heater vent when the control is set to DEF?

Re: How much defroster air?
 

These boxes came from factory flawed there is a half inch gap that will not connect the defrost to box.

Fix this with duct tape or similar product.

Remove the dash bezel, and dash to reviel the gap... Behind radio.

Good luck.

Ps this error was in 74 only but ive seen it on all years at the local junkyard
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Re: How much defroster air?
 

If you mean the "Y" shaped duct where it connects to the heater box, then I know what you mean. Mine does attach fairly well - no big gap but I will tape it up with HVAC tape.
I wonder if the adjustable rod on top of the heater box has anything to do with the flow of air to the defrosters. I can't remember exactly where it was before I took the box out, or how I would know how to adjust it. Does anybody have any ideas? Thanks.

Re: How much defroster air?
 

Yes! The y. Sorry i dont know about what levers do what.
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Re: How much defroster air?
 

where the rod goes in the floor /def actuator flap
there is ajustment for all 100% up/down or 75% either way

Re: How much defroster air?
 

Yes check that plastic clip on the door in the above pic...I replace mine 4 times already!

Re: How much defroster air?
 

i keep mine on defrost only, so i removed the cover on the floor vent and cut a peice of carb board to block it off. i few times i also nitice that my heater didnt work at all and cold air was blowing into the passenger side under the dash. there is a flap over there to control where teh air goes and the cable thing came off so it just flapped about.

Re: How much defroster air?
 

Thanks. I will experiment with that threaded rod setting. I have mine set at about where the picture shows it - seems like not quite full blast for defrost.

Re: How much defroster air?
 

To go 75% to 100 %,the flow from feet to head is done inside the "air box"
Can't see the holes from outside it,by the gas pedal
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