The easy-to-access control box and large access panels facilitate installing and maintaining the unit. Microprocessor controls monitor key points and provide diagnostics. Sentinel performance system monitors operation and signals the need for service before a lockout can occur. Double-isolation compressor-mounting system provides quiet operation. Compressors are mounted via rubber vibration isolators to a heavy-gauge mounting plate, which is further isolated from the cabinet base with rubber grommets for maximized vibration/sound attenuation. Ultra-quiet cabinet with extra insulation is available as an option.