auto climate weird knocking noise

[667theneighbour]

You don't have to line up the actuator. Just do the self-calibrate I explained earlier.

 

[EZStreet]

You don't have to line up the actuator. Just do the self-calibrate I explained earlier.

Rudolph- You'll need to line up the the teeth from the actuator comb and the vent door combs to where they have full range of motion after reinstalling the actuator motor. All the self calibrating in the world wont help if the teeth are lined up halfway down restricting full movement of the blend door.

 

[EZStreet]

Did you install the blend door actuator purchased from Rockauto.com? If so, did it fix the knocking/tapping noise? I have the same problem with my 2005 Tahoe right now and don't particularly want to pay $1500+ to get it fixed. If you would be so kind, can you walk me through the process of replacing the actuator or getting the doors to no longer stick?

And yeah, the motor was definitely stripped in the old actuator. When I opened it up the gears were all chewed up in one spot in particular which caused the clicking noise while the gears were missing eachother. Whatever you get, make sure you get the actuator for the auto climate system if you have auto clim. There are 2 types.

 

[scrnchr]

2004 Tahoe
NO Auto Climate Control


I just registered with this forum for this exact issue! Perfect.

Here is what I posted on another forum (got no answers):

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Our heater/defroster/vent system is making a "tick tick tick" noise. It sounds like it's coming from down around the heater box. The sound is of lower pitch than say a ticking clock, more like a "tap tap tap", I guess. It repeats in less than a second, like maybe 4 or 5 ticks/taps every 3 seconds. It is not completely regular--sometimes it misses a tick, sometimes a tick is a little louder or a little quieter.

It was already ticking before I replaced the blower motor resistor--no change, so I don't think it's something I screwed up.

The climate control can be on defrost, defrost/heat, heat, heat/vent or vent and it the ticking doesn't change at all. I thought it might be a loose piece of insulation flapping around in there, but the frequency of ticking does not change at all when I change the fan to any of the speed settings.

The ONLY thing I found that affects the ticking is the passenger side heat control. With the heat control slid all the up (hot), it ticks. When you slide it down one notch, it sometimes ticks, sometimes doesn't. Down another notch or more and the ticking stops. The driver side heat control does not affect the ticking at all. Obviously I am leaving the passenger side control down a couple of notches to stop the ticking. But I'd prefer to fix this.

So, can anyone tell me what's causing this? Is there some sort of limit switch that tells a flapper door motor to turn off, and maybe it failed and the motor keeps running and clicking a plastic clutch of some sort? A good diagram of this system would be helpful, if you can point me to that. And I do NOT want to pull the dash to fix this!!! Arghhhhhhhhhhhhhhhhh

Thanks.

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Two things posted above caught my eye...


667> might be the blend doors tapping if the door sensors are bad

Can you tell me more about the door sensors? Or maybe direct me to a diagram.


667> Have you tried calibrating the blend-door-actuator? Just disconnect the battery for a while, 15mins I read somewhere. Then re-connect and start the engine. Leave the climate control alone for about a minute while it self-calibrates.

Where can I read more about this? Also, doesn't that "recalibrate" the engine computer, i.e. won't it run really nasty for 5 or 10 minutes after the battery has been disconnected?


Thanks.





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[scrnchr]

Look what I found on a forum for the Uplander. Anyone know if this is valid for the Tahoe?

Alternate Method (w/o Scan Tool)


Clear all DTCs.
Place the ignition switch to the OFF position.
Connect all previously disconnected components.
With the Mode knob in the PANEL position, press and hold the AC button for 5 seconds.
Rotate the Mode knob fully counterclockwise.
Rotate the Mode knob fully clockwise.
Rotate the Mode knob fully counterclockwise.
Release the AC button.
Wait 40 seconds for the HVAC control module to self-calibrate.
Start the vehicle.
Verify that no DTCs have set as current DTCs.

There are many other calibration schemes online, but most require a "scan tool".


Also, most of them say to pull a certain fuse for 10 seconds rather than disconnecting the battery.
Which fuse would that be for the Tahoe?



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[667theneighbour]

Rudolph- You'll need to line up the the teeth from the actuator comb and the vent door combs to where they have full range of motion after reinstalling the actuator motor. All the self calibrating in the world wont help if the teeth are lined up halfway down restricting full movement of the blend door.

Sorry. I meant you don't have to line up the actuator to match the settings on the controls. My bad.

 

[EZStreet]

Sorry. I meant you don't have to line up the actuator to match the settings on the controls. My bad.

I wouldnt have had to line up anything if I had just removed the actuator off the gear instead of pulling the whole thing out :mad2:

Oh well live and learn

 

[scrnchr]

I tried the calibration scheme I posted on 2/18. It didn't seem to do anything--still have the ticking. Can anyone point me to the documentation for the blend door actuator calibration for a 2004 Tahoe? Thanks.

I'm on some boating forums and someone usually has links to an online copy of the manufacturer's repair manuals. Are there no Tahoe repair manuals linked online somewhere?

 

[Fudge]

Yup

Mine does this strange sound on startup but only lasts a few seconds. But, it does come back when I've driven for awhile. My first thought was something had fallen through the dash onto the fan/blower. If it gets worse I'll be looking for that write up (with pics, lol).

 

[scrnchr]

I don't mind doing the looking for the information, I just need someone to point me to where to start. I was hoping to find some Tahoe repair manuals online, with some systems diagrams that would help troubleshoot these things.

 

[EZStreet]

i have a Hanyes manual which is pretty good as far as step by stp repair guides, if you can find a GM shop manual that the techs use thats even better.

Ebay's your best source for both.

 

[scrnchr]

Does the Haynes manual have good photos/diagrams of the blend door actuator, and maybe a description of the actuator calibration scheme? I have a Haynes manual for a car that I have, and it seemed like a good manual until I started doing repairs with it. Then I found out that a lot of photo detail just wasn't there.

 

[scrnchr]

Years later and the stupid thing is still knocking. Has anyone found a calibration method that works? Thanks.

 

[DENALI_101]

they can be reprogramed by the dealership. everytime u disconnect the battery you need to possibly reprogram the actuator. the actuators only last a couple of yrs usually. i have replaced mine both driver side and pass. and they are due again to get replaced. i have a 2004. the part cost $250ish from the dealer and you just have to lean under passenger side dash to replace them(black box about the size of deck of cards). kinda tight but doable in under 1/2 hr in your driveway.

 

[advproducer]

they can be reprogramed by the dealership. everytime u disconnect the battery you need to possibly reprogram the actuator. the actuators only last a couple of yrs usually. i have replaced mine both driver side and pass. and they are due again to get replaced. i have a 2004. the part cost $250ish from the dealer and you just have to lean under passenger side dash to replace them(black box about the size of deck of cards). kinda tight but doable in under 1/2 hr in your driveway.

Could a bad actuator also be the cause of hot air (like max heat) to randomly blow out of the front vents even though AC is on/working correctly? Shutting off the engine and restarting causes the AC to return to normal.

 

[DENALI_101]

Yes that's what it causes. I'm temped to put in a switch on the main power wire going to the heat control module. That way u don't have to shut off the car everytime u could just flick the switch off then back on. Til it get to happening all the time. Cause it's so random it's a pain to fix it.