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Discussion Starter · #1 ·
My '77 Impala has the air-blender system; 3 pulleys under the steering wheel (Left-Center-Right) and a 3-way blender slider in the middle console (Vent-Heater-Defrost). I do not have any vents on the driver or passenger upper dash, they are just solid plastic pieces that sit where those vents would be. Instead, my 2 side vents are underneath the dash.

Anyways, my issue is that the driver side is the only one that blows air from the fan when it is in heater or vent mode. Whenever I open up the center and passenger vent via the pulleys under the steering wheel all I get is air from outside, not from the fan. The vent and heater settings seem to operate very similarly, but I get less hot air out of the driver side when the vent is selected. I basically have to drive with only the driver side vent open in the winter, which makes it take awhile for the car to heat up. In the summer the only cold air I get is from the air blowing when the car is moving except for the driver side vent.

The defroster works fine.

I already nailed down the issue as a probable blender door issue, but I'm not 100% sure where to access it or how to fix it when I get to it. It would take a large effort to access the heater core and the innards of it through the engine bay, and I didn't see anything jump out at me when I removed the glove box.

I have had this issue since I bought the car 3 years ago.
 

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Wow you have an unusual system there, I am not familiar with it at all. I have checked my FSM and it shows what you are describing. I am glad to hear that the defrost works well. At least that is showing that the heater core and air movement are sufficient. According to my manual you are having air leaks or blockages in the system. It first suggests making sure that the control cables are moving from stop to stop on the intended doors, if not you will need to make adjustments on their movement. It also suggests checking the door seals of the blend doors to be sure they are intact. Also if your vehicle has rusted out rocker panels, floors then you may have a big issue there.

The temperature blend door is out under the hood with the heater core, I don't think this is your problem.

When the air is blowing where does it seem to go if not where you want it to?

The center vent door is behind the center of your dash, you may need to pull the radio and heater bezel off of the dash and those units out to see if that door moves with the selector, if not then fix it. If it is then you may have a blockage somewhere in that portion of the system.

Let me know what you find and I will continue to try and help you fix this.
 

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Discussion Starter · #3 ·
I will check those things when I can. Up until I owned it, it has never seen too much of a winter. My dad has a 1984 Caprice with an almost flawless body, and yet his undercarriage is a lot more rusty underneath than mine, so I'd like to think it's highly unlikely anything has rusted that much anywhere inside the car. Mine is actually very surprisingly clean for the age of the car-no large rust flakes or pitting, and only one small dime-sized hole in the frame. How would I check the cables? Just by pulling them out individually as much as I can and tugging on them? I'm sure I could readjust them like that if that was the issue. I heard some stories of things being lodged in the doors, but I can hear them open and close, maybe not fully but that may be the issue. I also hear the fan very well through both of the vents that don't work, it's quite strange.

When I have everything open in heater mode it just comes out the driver side and the middle and passenger vents just have air coming from the outside, no matter what setting the vent/heater is on. If the car is sitting still I don't get any sort of cold or hot air out of the two. I really have no clue where it's going then.

And yeah, I know it's quite an unusual setup, I can't find much info online about it. I also have a 250 L6 (that still runs like a top) if that helps at all.

Thank you.
 

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I take it that this is a non A/C car right?
if so you will have to make sure the leavers are hooked on at both ends, and move freely from one side to the other. There is a thud sound as the control flaps hit inside the heater. these may need ajustment.
Some times there is a object falls in the defrost vent and messes with the controle. I have in the past had to pull off the vent deflector for the floor heat (under the dash on the trans hump) and slide the heat defrost knob back and forth till the objects fall out.
 

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Discussion Starter · #5 ·
I have in the past had to pull off the vent deflector for the floor heat (under the dash on the trans hump) and slide the heat defrost knob back and forth till the objects fall out.
I will try that. I am surprised that's what that is though. I know exactly what you're talking about, but my air on the floor seems to be coming straight from under the dash and not from the deflector so much. And yes, no A/C.
 

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Have you tried to trace where the air is flowing from? You can use a piece of paper to see if you can tell where the air is coming out of from the heater box.
 
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