Bard 8612-043ABX MC4001 Advanced Solid State Dual Unit Lead/Lag Main Controller Board

The Bard 8612-043ABX is the OEM MC4001 Main Controller Board — an advanced solid-state dual unit lead/lag controller designed for Bard HVAC systems. This board serves as the central control hub, managing heating and cooling operations across two connected air conditioning units to maintain efficient, reliable performance in demanding applications.

The MC4001 operates on a lead/lag control strategy, automatically rotating operation between two paired HVAC units to balance runtime and extend overall equipment life. It supports programmable cooling and heating set points, and features a front-panel 4-character digital display for real-time temperature monitoring and system programming.

Key Features:

• Advanced solid-state dual unit lead/lag control architecture
• Input power: 18–32 VAC, 50/60 Hz — powered directly from connected A/C units
• Isolation circuitry eliminates the need for line or low-voltage phasing
• Backup power support: accepts –24VDC or –48VDC (–20 to –56V) to maintain microprocessor operation during power fluctuations
• Programmable cooling and heating set points via front-panel interface
• 4-character front-panel display for temperature readout and programming
• On/Off and Comfort buttons for intuitive operation and quick set point adjustment
• Compatible with economizer-equipped systems and electric heat configurations
• Compact metal enclosure: approximately 13.5" H x 9.25" W x 3" D
• Genuine Bard OEM replacement part — restores system to factory specifications

The MC4001 Main Controller Board is well-suited for telecom shelters, modular buildings, equipment rooms, and other mission-critical environments where coordinated dual-unit HVAC operation is essential. Part number 8612-043ABX is the direct OEM replacement board for compatible Bard lead/lag control systems.