Heater locked on heat? Help fixing actuator?

2000 Chevrolet Silverado 5.3 LT (Single-zone climate)
Let's say I start my truck with the temperature on cold. I drive along and then turn my temperature to hot. At that point, no matter
what I do, my temperature stays on hot, even if the dial is aimed at cold. I was told by a mechanic friend that I need to remove and lubricate something under the passenger dash. I think he may have said actuator. He also mentioned that I should leave one of the screws out even when I'm done.
Can anyone give me specific instructions on how to this, preferably with pictures?
Thanks.
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Blend Door? Mine gets stuck. Did any gasket material fall out out of the bottom ducts recently?
Cheers
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That sounds about right. How does one fix a stuck blend door?
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This may be worth something.... (read all the posts) <http://www.automotivehelper.com/topic574779.htm
Cheers
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Awesome, Martin. Thank you.
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...
I have the same truck, same problem. I found that if I don't turn the heat all the way to the 3 o'clock position and leave it at maybe the 1-1:30 position it doesn't get stuck.
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