Clicking behind dash on start up

Tiny
CHRISTY379
  • MEMBER
  • 2007 HUMMER H3
  • V6
  • 4WD
  • AUTOMATIC
  • 185,000 MILES
Sometimes when I start my Hummer there is a repetitive clicking. It is absolutely coming from the dash area. It lasts for a few seconds so maybe 8 clicks. This is a new development. I have been having problems with it stalling out when I decelerate from anything over 10mph as well. The stalling happens between 20mph and 10mph.
Thursday, February 3rd, 2022 AT 6:58 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

This is a tough one because the relays for the vehicle are in the under-hood fuse box. Often times a clicking behind the dash is the result of an HVAC door actuator. There are small gears in them that fail and can cause what you described.

If you take a look at pic 1 below, I indicated where the actuators are. If possible, locate them, and one at a time, place your hand on them to see if you feel the clicking.

As far as the stalling, that (at this point) sounds like a different issue. The first thing I would recommend is checking for engine vacuum leaks. A leak can cause a stalling issue when the engine reaches idle. (Slowing down).

Here is a link that explains how to check and repair leaks:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know what you find or if you have other questions.

Take care,

Joe

See pic below.
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Thursday, February 3rd, 2022 AT 8:09 PM
Tiny
CHRISTY379
  • MEMBER
  • 2 POSTS
Thanks for the vacuum leak information, I'll look into that. I don't believe the clicking has anything to do with the HVAC Door Actuators because it stops as soon as I step on the gas. I tested it today and it will literally keep clicking until I step on the gas pedal. I'm at a total loss with this one.
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Thursday, February 3rd, 2022 AT 10:05 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Do me a favor. Since it stops when you hit the gas, I'm questioning if there is an evap sensor on the firewall under the hood making the noise (and possibly causing a vacuum leak). When you hit the throttle, the engine vacuum drops because you open the throttle plate on the throttle body. If that is stopping it, this could be the issue. It's a theory at this point. However, the idea that vacuum drops and the noise stops it is a bit too curious for me.

When you get a chance, before starting it, open the hood. Start the engine and see if you can hear it under the hood near the firewall.

Take care and let me know when you can.

Joe
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Friday, February 4th, 2022 AT 6:20 PM

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