What is the schwa vowel sound in accessory?

The schwa sound in "accessory" is in the first syllable, "ac".

The schwa sound is represented by the symbol ə and is a very short, unstressed vowel sound. It's the most common vowel sound in English, and it often occurs in unstressed syllables.

In "accessory," the "a" in "ac" is pronounced with a schwa sound.