I've looked in the Nissan book that came with the truck but found nothing. After shutting the armada off and waiting about one minute, there is a sound that comes from somewhere behind the steering wheel. It's a mechanical sound, like something is pressure-locking. The sound itself lasts for about 2 seconds. I recently noticed the sound at start-up as well. I never would have noticed it if I hadn't heard it while the engine was off and all was quiet.

so far my theories are:
Some kind of super steering-wheel lock...
or, parking break assist...? I think if the Armada was parked on a slope it might benefit from some kind of power break-lock.

I have learned of so many things that are under the hood of the Armada that nothing would supprise me at this point. If anyone knows what this sound is, and I know you do, Please let me know.
Thanks!

I've heard that sound, I assumed it was some sort of steering lock too. Now I'm curious...

i thought it had something to do with the outside air door opening up in the HVAC??!!! i hear it twice.. ive always heard it and it freaked the heck out of me when i first heard it...

i thought it had something to do with the outside air door opening up in the HVAC??!!! i hear it twice.. ive always heard it and it freaked the heck out of me when i first heard it...

I believe you are correct

Here is what I think:

If your AC is on and in the Recirc Mode, when you turn the engine off, the outside air damper will open (vacuum-type actuator), probably due to the computer onboard. Now, I am an HVAC craftsman by trade and when I had my POS '99 Explorer, I used to turn my AC off before I shut the engine (to reduce load on next start-up) and place the blower switch in the Fresh Air mode. When I did this, the same type of sound was heard due to the vacuum actuator releasing the pressure. This helps to dry out the evaporator while parked and to ventilate and cool the vehicle instead of leaving it all shut to the outside during a hot day in the parking lot. It also helps prevent the mildew smell in the vehicle when parking it in cold darker places like underground parking garages.
I think the Nissan engineers put all their brain power into this vehicle. AND BOY, AM I ENJOYING THE RIDE!!

BTW, this AC system for the Armada is the best desgned one I ever seen both operationally and practically.

Dex

1: It does make scence that it's the HVAC

2: It opens even if you don't use the A/C. I never do, as it never gets much hotter than 70degrees in August here.

3: I was a lot happier when i thought it was some super-secret, hight tech security feture that only Armada owners had:D

haaa @ #3... yeah kinda lets the.. ahem.. " air " out of it eh... no pun intended of course...

Finally a potential answer to the question I've had about my truck for quite a while...

The Armada uses electric servos on all the A/C-Heat doors and dampers. No vaccum is used. The sounds you hear are the servos running, closing the dampers. If you watch your instruments after shutting off the engine you will see the needles give a "jump" after a while. This is the system powering down.