Mode Actuator Repair/Replacement

[east302]

Each damper has a flexible rubber edge to it. They tend to deteriorate and leak air, so that may be what you’re seeing. If you have a boroscope camera, you might be able to spot something through the floor vent. It’s kind of academic though - the dash would need to come out to replace the dampers.

This is a floor damper below with the deteriorating seals - it’s the same concept for the other two. New versus old:

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Here is an old box with defrost on left, panel on right. The perimeter seals are gone. Air just kind of went wherever it wanted which sucked in the summer.

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New dampers:

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[Supercharged111]

Are the dampers available in 2024? It'd suck to tear it down, find the problem, and be unable to get parts. I suspect I have a leak at the firewall as well, the one @Schurkey mentioned having that required foam tape to plug.

 

[east302]

Rockauto has them

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Or you can get the lower box (GM #52467204) which includes dampers 155520 and 1550552. I broke my box trying to get the arms off of the dampers. They were pressed on and stuck pretty good.

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[Supercharged111]

Me either. I need to get off my dead *** and pop that cover off for a start.