chòng is the rarer reading — mostly seen in 冲劲 (drive, gumption), 冲着 (facing; for the sake of), and a handful of adjectival uses meaning 'pungent' (smell) or 'forceful' (manner). Traditional form is 衝; the water-radical 沖 never carries this reading.
grammar
As a coverb, 冲 + object means 'facing / aimed at' or 'on account of', similar to 对 but with sharper directional energy: 这股冲劲 ('this burst of drive'), 冲着面子 ('for the sake of face').
Under the chòng reading the simplified 冲 stands for traditional 衝, whose original radical was 行 (go/walk) — fitting the 'charge / face towards' sense. The ice radical here is a simplification artefact, not semantically related.
Phonetic: 中 → chòng (initial shift, tone change to falling). The target-pierced-by-banner image of 中 resonates with the chòng senses of forceful drive and head-on facing.
