ttc,
Most, if not all, 'Auto' drains are just an overflow port that empties into your deck drains...
Mine is just a pipe with a cover that is mounted just below the coping, as the water fills up in the pool, anything much higher than about half way up the skimmer will just drain to the street. It is quite obvious, it is not hidden..
I have heard of others that drain through a hole in the back of the skimmer.
My guess is that you do not have one.
If possible, you do not want your pool water to get above the bottom of the coping.. Water will try to flow between the coping the bond beam and compromise the joint.. Probably not a major issue for this to happen once, but you would not want it to happen over and over...
If you have a hose bib, or garden hose faucet, at your equipment pad, you can open that while running the pump and it will allow you to drain some of your pool.. you just have to watch it like a Hawk so you can prevent the water from getting below the skimmer mouth. It would of course make sense to have a hose attached to get the water away from your equipment...
Thanks for posting,
Jim R.