Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Hello guys,

I have a 2006 LT EXT model recently bought. Every time I turn on the vehicle, there is a weird noise that comes from the rear end. Its sound like a motor self testing and runs for a brief and then stops on its own. Its definitely inside the vehicle. It also happens at every startup and the engine does even have to running for that. Can you guys please help me figure that out.

Thanks,
MR
 

·
Registered
2004 chevy trailblazer_ls_ext
Joined
·
404 Posts
The only electric motors back there are the actuators (and blower motor) for the rear heat/AC unit on the passenger side. They are probably doing a calibration sequence. You could pull the cover off the unit and look for anything caught in them, but if the noise only lasts a second or two they are probably fine. If one of them clicks for a minute or so then it's failed and needs replaced. There are two of them, both the same part number. Be careful removing them, because if you break the plastic rod they attach to the project just got a lot more complicated! You could also try unplugging them one at a time and see which one is making the sound.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #3 ·
Thanks man. It lasts for about 30 sec. Let me try your suggestion and see what happens. :)
 

·
Registered
2004 chevy trailblazer_ls_ext
Joined
·
404 Posts
Thanks man. It lasts for about 30 sec. Let me try your suggestion and see what happens. :)
If it lasts that long, I'm betting one of the actuators has failed and is trying to reset itself. I had this happen on my '04 TB EXT. There are a number of YouTube videos about replacing these.
 

·
Registered
Joined
·
2,018 Posts
Question for you both:

On MY 05 TB EXT, the rear blower will not activate until there's either sufficient hot coolant at the rear heater core and/or the blower will also not activate until the rear evaporator is sufficiently cool to deliver chilled air to the rear seat.

This is every time I either turn the rear system ON to heat or cool or the rear passenger(s) set their controls to run hot or cold.

Same thing - the blower will not activate until it can do what is requested of it.

I also wonder if the OP is hearing the supplemental blower that gets the cat to incandesce.

Ooops -- I just notice the OP has an EXT and I don't think the EXT has that auxiliary air injection blower. Sorry.
 

·
Registered
Joined
·
101 Posts
Question for you both:

On MY 05 TB EXT, the rear blower will not activate until there's either sufficient hot coolant at the rear heater core and/or the blower will also not activate until the rear evaporator is sufficiently cool to deliver chilled air to the rear seat.

This is every time I either turn the rear system ON to heat or cool or the rear passenger(s) set their controls to run hot or cold.

Same thing - the blower will not activate until it can do what is requested of it.

I also wonder if the OP is hearing the supplemental blower that gets the cat to incandesce.

Ooops -- I just notice the OP has an EXT and I don't think the EXT has that auxiliary air injection blower. Sorry.
30 seconds is a looooong time for the AIR pump to run. Unless the op was exaggerating. I don't ever recall it running that long even when it's below 0. If the op could just take a cell phone video or at least describe the sound a little better it would help.

Also I can hear my fuel pump humming when I turn the ignition on. Every time. Till pressure is built. It's like a high pitch hum. Maybe that's it?
 

·
Registered
Joined
·
2,018 Posts
@ Ock ----> we're on the internet and neither of us are anywhere near the vehicle ---- requesting a video is a very good idea.

Make that a L-O-O-O-N-G video.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #9 ·
Hello guys,

It turned out to be the DVD player and the actuator. Thanks for your help.
 
1 - 11 of 11 Posts
Top