Continueing problem with Atmos AI

I purchased a new Aeris Atmos AI this past February and made over a dozen dives with the computer to depths of 90 feet. The default display on the computer is supposed to show remaining No Decompression Limit time available for the dive, with a secondary display which can be accessed which will show remaining air time.
My first AI continually displayed remaining air time and I was never able to access the NDL display. I contacted Aeris and they asked that the computer be returned.
I received a new computer about two weeks later, and now have just 5 dives logged, all while working with an OW class, which means depths never went below about 30 feet. I had the same data display issue with the replacement computer. In other words, I still only got remaining air time and not the NDL. It occurred to me, however, that since I was diving at shallow depths where I would run out of air long before NDL time, perhaps the computer defaults to the remaining air display until I descend to a depth that requires the NDL to become available. I don't find any reference to this in the manual, but would anyone happen to know if this is the case?
Unfortunately my diving is over until spring, due to family commitments, and by the time I get back into the water the warranty will be expired. Thanks for any input.

As I understand it, the computer will show you either NDL or DTR, whichever is less, but not both.

I think you have a misunderstanding of the main display.
It shows a "Dive Time Remaining" or DTR which is the most limiting time:
AIR, N2, or O2. See page 18 of the manual.

You were probably air limited on the 90 ft dive as well.
(or at least the computer thought so).

The Air time remaining calculation can be off/tricked during
the first few minutes of a dive because of the pressure
drops due to things like inflating your BC and air temperature
drop. If you have a warm/hot tank and then jump in cool water
the pressure can easily drop up to 200 PSI. This can temporarily
give a much shorter ATR. This will correct after a minute or
so of reaching a steady state.

The ATR calculation also takes into consideration the end
pressure (as set in the end pressure alarm), the air needed
for the ascent up to the safety stop, and the air needed for the
safety stop as well.

If you set a large value for your end pressure alarm, the
ATR calculation will give you a very short amount of time
as it is trying to get you back to the surface with that amount
of pressure. (I believe default is 500 or 550)

Have you gone through the numbers to see if indeed your
SAC rate is low enough to allow nitrogen to be the controlling
factor?

Just some ideas.

--- bill

Cool. Glad its working for you.
I really like the ATMOS AI too. My wife and I now have 170 dives on ours.
No issues, other than occasional download synchronization with the cable,
which is due to residual moisture and is easily resolved.
When the time comes, you will love how easy it is to change the
battery.
Literally takes all of 30 seconds and you can even get batteries at Walmart.


--- bill

Sounds like my plans to buy one of these is not a bad plan.

Glad I found this thread as I have been trying to work this out on the last two dives !

Both have been less than 9 metres so it always displays the air time only.