96 Tahoe AC issue

[Babylon]

Howdy

Intermittently whenever I start my AC it will be quiet and feel like no air is coming out of the vents

If I press the AC button a few times on and off, you can hear a loud "THUNK" and the AC now blows hard out of the vents and sounds like it's running normal

What the hell is causing this?

 

[TreeGeared]

Good morning. Nothing like a little guess the noise trivia first thing in the morning.

Since it was an all caps "thunk" I am going to hypothize it is blend door issue. Now was it a by your feet thunk a, passenger side thunk, or buried in the labyrinth of the dash thunk.

 

[Babylon]

Good morning. Nothing like a little guess the noise trivia first thing in the morning.

Since it was an all caps "thunk" I am going to hypothize it is blend door issue. Now was it a by your feet thunk a, passenger side thunk, or buried in the labyrinth of the dash thunk.

It sounds as if it's by my feet but middle of the dash by my feet, if that makes sense.

 

[TreeGeared]

Ah good, that is the easy one to get to. May be a sticking blend door actuator, or it could be the control panel for the AC controls themselves. Probably need to use a multimeter to check if the signal to the actuator changes as you adjust the controls.

 

[Babylon]

Ah good, that is the easy one to get to. May be a sticking blend door actuator, or it could be the control panel for the AC controls themselves. Probably need to use a multimeter to check if the signal to the actuator changes as you adjust the controls.

Thank you! Will report back!

 

[someotherguy]

Look under your dash, find the sliders on the actuator towards the driver's side, GENTLY clean them - they're delicate. They're lubed with white lithium grease (or similar) from factory and the lube gums up over the years, making them sticky. You can do a quickie clean by laying down some newspaper on your carpet and spray the sliders with WD40, work them by hand a bit (again, GENTLY) to free them up. Apply a little fresh white lithium grease.

The THUNK is the actuator motor finally overcoming the stickyness of the old lube and letting the slider/spring arrangement push the door into the requested position.

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Richard