2 weird issues: 1. Clicking when AC is on, and 2. humming sound from brakes

[Diggerdan11]

So i have 2 weird issues going on with my Tahoe right now and im not sure what exactly is going on.

#1 When i turn my AC on (especially when i turn on MAX) there is a weird clicking sound. it sounds like a ticking clock and is every second like a clock. The sound seem to be coming from under the dash and is much more noticeable from the drivers side. When I turn my HVAC off the sound goes away, when I turn it back on the sound comes back after a bit

#2 there is a humming sound coming from the brakes. You know the sound ABS make when they kick in, well that’s the same kind sound my brakes are making, but this happens right after you start up the Tahoe and put it into gear. It does not do this all the time, but it seems to be worse after the Tahoe has been sitting for a while, like when I drive it for the first time in the AM. You can feel a slight vibration in the brake pedal when it makes the noise. It does not make this noise when driving, and it usually only happens after sitting for a while

Does anyone have any idea what might be causing these 2 unrelated issues?

 

[jem556]

My 03 LT does #1 sometimes...its related to the fan blower, because if I turn the fan off for a few seconds and then back on, it will stop the ticking. Let me know if you solve it!

 

[blueflamed03]

mine ticks with AC as well...

 

[BananaHANDS]

Same here for #1 so very annoying.

 

[03YukonNH]

For #1, I have the same problem. I have narrowed it down to a problem with the actuator for the blend door that directs air flow to the defroster, floor or dash vents. Try pushing the button on the hvac controls so you direct the A/C to the floor. The noise will most likely go away.

As for how to solve the problem...I don't know yet. I probably need to replace the door actuator under the drivers side dash.

 

[Diggerdan11]

so it sounds like my AC issue is common, I dont hink i need to worry about it too much. It only happens when i run my AC and that is only a couple months in a year

Now does anyone have any ideas on #2? its scares me a bit

 

[UBILLN]

I have issue #1 too and I agree that its probly a blend door actuator on the fritz, eventually it will just go out completely and can be dealt with then. This noise is accompanied by my rear a/c fan always running even when the rear fan control is off. It only stops when the entire a/c system up front is turned off.

 

[msbailey]

I have the same #1 problem. It's certainly the actuator for the blend/defrost door. I just haven't gotten around to fixing it yet.

 

[UBILLN]

Yep, one of those "dont fix it if it aint broke" things...

 

[03YukonNH]

For #2 I think I know what you mean because it happens to me almost every morning. When you take the truck out of park, the transmission causes it to lurch forward. This is especially true in the morning when the truck first starts because its cool out and the idle is kinda high. When you take it out of park and the brakes have some mist/dew on them the truck breaks free a bit until the brakes grab a second later. The noise is just the pads vibrating against the rotor. At least thats what makes the noise I have...