This industry comprises establishments primarily engaged in manufacturing ventilating, heating, air-conditioning, and commercial and industrial refrigeration and freezer equipment. Illustrative Examples: Air-conditioner filters manufacturing Air-conditioning and warm air heating combination units manufacturing Attic fans manufacturing Dust and fume collecting equipment manufacturing Gas fireplaces manufacturing Heating boilers manufacturing Industrial and commercial-type fans manufacturing Refrigerated counter and display cases manufacturing Refrigerated drinking fountains manufacturing Space heaters (except portable electric) manufacturing Establishments primarily engaged in--