I just purchased a used XL15s. The unit when in manual mode emits an oder, but the air feels oxygenated. When you breath close to the machine the air seems to irritate or kinda burn my eyes. When in auto the air feels and smells like the existing room air. Is this normal?

This is what the machine is designed to do! The machine emits a low amount of ozone, which is the purifier/sanitizer created by sunlight. Close to the machine, it's concentrated. When it spreads throughout the room, it kills odors and bacteria, and creates the fresh smell of clean air. The air truly is "oxygenated," because ozone is simply O3, instead of O2, and breaks down quickly.
If the numbered dial is set too high (try it at 300 to 500) it will smell "bleachy." Your "rule of thumb" is that when you've been away, and enter the home, you should experience the same fresh, clean smell that you get when you step outdoors on a bright spring or winter day.
When you're doing something that creates odors, like frying fish or cooking sauerkraut, turn the dial up to take care of that odor quickly, then turn it down for normal operation.
Leave it on the manual setting for continual purification. Often, the auto setting has been disabled, which might be the case in your older machine. (These machines can be 12-15 years old!) For an owners manual, go to www.vollara.com (new name of Ecoquest/Alpine). They may be able to help you.