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Discussion Starter · #1 ·
I’m having some trouble with my 1997 GMC Suburban k2500 with a 496 stroker. The upper A/C vents (that blow air directly on you) will not blow any air out. I have replaced the A/C controls, and the blend door actuator. While I had the actuator off, I moved the blend door mechanism with my fingers to the upper vent position and nothing came out. The actuator is turning as it should. Blower motor is working strong, and the lower vents as well as defroster both work. The A/C itself is not charged and does not work at this time. I don’t see how this could be related to my issue though. I would appreciate any suggestions.
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Does your model have cabin air filters? Have you cleaned the ducts out or scoped them to look for blockage?
 

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‘01 Silverado 2500HD 8.1/Allison 5sp xcab long bed
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Unfortunately, this probably means the baffle in the plenum is broken.
 
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‘01 Silverado 2500HD 8.1/Allison 5sp xcab long bed
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The plenum would be the main ducting system that sits behind the HVAC controls. That rod shifts the various “doors” or baffles, to direct airflow up to the defrost vents, down to the floor, through the center of dash vents, etc.


Also, good thought about the filter, but this gen doesn’t have a cabin air filter.
 
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I believe I am having the same problem, we'll a similar problem, my driver's side temp does not change, the actuator works fine; but the door doesn't move.
I'm thinking of removing the blower motor and getting my hand in there to see what's jamming/blocking it.

That's what Greg is suggesting you try
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Thanks for the info, Greg.

Having pulled mice out of my AC ducts multiple times and now knowing there are no cabin filters, I would definitely check the duct work.
 

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Discussion Starter · #8 ·
The plenum would be the main ducting system that sits behind the HVAC controls. That rod shifts the various “doors” or baffles, to direct airflow up to the defrost vents, down to the floor, through the center of dash vents, etc.


Also, good thought about the filter, but this gen doesn’t have a cabin air filter.
So I’m assuming that the only way to fix this is to take the entire HVAC box out from under the dash? And this would also mean removing the dash to get to it?
 

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‘01 Silverado 2500HD 8.1/Allison 5sp xcab long bed
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It could. Verify that the individual functions work, or don’t work, by adjusting the operating rod manually first. I believe you said you already did, though, correct?
 

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Discussion Starter · #10 ·
It could. Verify that the individual functions work, or don’t work, by adjusting the operating rod manually first. I believe you said you already did, though, correct?
Yes, I took the blend door actuator on the driver side off and manually moved the rods with my fingers. The bottom vents work perfectly, the defroster works on the passenger side only, and the top vents don’t work at all. I am currently doing a radiator replacement, so I can’t start the truck to test it again. I’ll definitely look at it I though once I have it running again.
 
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