Blue 4" Universal Features Large, 4-square-inch blue display with easy-to-see characters. Active protection for systems with Comfort Alert™ CA2 module compressor diagnostics. Keypad lockout. Quick one-button programming (See Automatic Schedule section in installation instructions). Configures as manual heat/cool, auto changeover, heat only or cool only. Exclusive Cool Savings™ feature saves energy during peak A/C demand periods. Adjustable setpoint temperature limits. Hydronic 2 or 3 wire zone valve applications. Battery power monitor.