Defroster Question
 

Today is the first day we have got any serious rain this summer. My truck is an original A/C truck with everything working. The slides on the HVAC control move freely from one side to the other and I had it set to defrost to keep my windows from steaming inside but that didn't work. Realizing the 72 has only 2 small ports for defrost to hit that big front window is the steaming normal on the trucks. Even with the fan on high I can blow harder ( and no, I'm not a blow hard ) than the air coming out of the ports.

Re: Defroster Question
 

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Are you sure that the control is actually opening the defrost door? Does the heater & A/C work good? Three possibilities that I can see, The defrost door is not opening, the heater boxes are full of debris or mouse nests, or the heater core is leaking. The leaking heater core will not cause lack of air flow but it will make your windshield steam up....

LockDoc

Re: Defroster Question
 

Heater core is good. It does take along time for the temp gauge to move up but the truck gets warm when up to temp. Is there doors on the heater boxes and is the defroster door visible form the cab. I have to fix this because i want to take this truck on the long haul Power Tour next year or the year after and I'm sure I'll be driving in the rain at some point.

Re: Defroster Question
 

I am not that familiar with the A/C stuff but yes there would be a door or flapper to control the air to the defroster ducts and vents. Are you sure that the air ducts haven't come off of the heater outlets or the dash vents? That would be an easy check. (I think)..:)

LockDoc

Re: Defroster Question
 

lo0ckDoc is right, the low hanging fruit is easiest to pick. Mine had the vent hoses rotted out. If the heater blows harder than the defrost, that is a good sign this is the problem. Mine's heat only but AC would do the same thing.

Re: Defroster Question
 

I never thought of the hoses. My last truck they were gooped and duct taped together. I'l start with the hoses. Maybe after 43 years they could be a little rotten.

Re: Defroster Question
 

the flapper valve in the black box on the floor usually craps out causing poor air distribution

Re: Defroster Question
 

That valve was bad on mine, replaced it and got good defrost again

Re: Defroster Question
 

Thanks Tommy, That is why this site is so great everyone helping each other out. By the way, the P01's I got from you look great on the truck and I've had lots of compliments on them.

Re: Defroster Question
 

Could you send a pic of the where the flapper valve is located because I see nothing that looks like door or valve in the front the heater box.

Re: Defroster Question
 

I'll get a pic tomorrow. And I'm glad you're happy with the covers. I spent a lot of time on those. Tried to get them perfect

Re: Defroster Question
 

This is the part that has the flapper inside it.:chevy:



http://i.ebayimg.com/00/s/MTI4MlgxMj...VZQ~~60_35.JPG

Re: Defroster Question
 

Thank you Andy.

Re: Defroster Question
 

There ya go, Andy beat me to it

Re: Defroster Question
 

Now to get it out of the truck. I get intimidated when I have to do stuff on the truck I haven't done before but it always seems too work out as long as I have enough time and take my time, and when its done and I've fixed the problem I always feel good. Working on my trucks over the years and accomplishing things has boosted my self confidence.