Lennox LB-90182A IMC G1-2 Gas Valve Control Module Board A58 | Cat # 56K85 | Integrated Modular Control

The Lennox LB-90182A (Cat # 56K85) serves as the high-level "brain" for commercial rooftop units, specifically functioning as the A58 Gas Valve Control Module within the Integrated Modular Control (IMC) system. This OEM-focused G1-2 generation board is responsible for the precise sequencing of the gas valves, ignition, and flame sensing circuits. Engineered for Lennox L-Series and S-Class commercial units, this module translates commands from the main M1 board into mechanical heating actions. By replacing a faulty A58 module, you restore the system's ability to communicate between the "body" of the burners and the central IMC intelligence, ensuring safe combustion and preventing mid-winter heating lockouts.

Key Features

• Genuine Lennox IMC G1-2 Logic: Specifically engineered for part number LB-90182A, maintaining factory-standard ignition timing and gas valve modulation for commercial L-Series units.
• Integrated Gas Valve Management: Actively monitors the A58 circuit to fix issues with failed ignition attempts, intermittent gas valve drops, or "no-spark" conditions.
• Advanced Flame Rectification: Features high-sensitivity circuitry to resolve nuisance flame failure codes, ensuring the "brain" accurately detects a safe burner flame.
• System Communication Bridge: Provides seamless integration with the IMC M1 master controller, allowing for remote diagnostics and clear error reporting via the system's digital display.
• Safety Protocol Monitoring: Continuously scans the heating loop for limit trips and pressure switch fluctuations, shutting down the gas train instantly if a hazard is detected. 

Product Details

• Brand: Lennox
• Manufacturer: Lennox Industries
• Part #: LB-90182A
• Catalog #: 56K85
• Generation: IMC G1-2 (Integrated Modular Control)
• Module Type: A58 Gas Valve Control
• Weight: 0.95 lbs
• Voltage: 24 VAC
• Application: Commercial Gas/Electric Rooftop Units 

🛠️ HVAC Depot Pro Tip

Take a Picture First: Before disconnecting the multi-pin plugs or the spark ignition wire, photograph the board's orientation and terminal assignments. On IMC systems, the A58 board is often mounted in close proximity to other modules; a photo ensures you don't cross-wire the communication bus. Conduct a diagnostic check by viewing the M1 master board's display for "ECTO" codes after installation to ensure the new 56K85 is being recognized by the network. Always ensure the ground connection to the burner tray is clean and tight, as a poor ground is the primary cause of flame-sensing errors on this module. 

Cross-Reference

• Superseded / Legacy: 56K8501, 10M52, 97L48, LB-90182
• Drawing Numbers: 100467-01, 100467-03
• White-Rodgers/Emerson Equivalents: 50A62-120 (OEM Specific)
• System Equivalents: A58 Module, IMC G1 Generation 2

Model Compatibility

• Lennox L-Series (Suffixes: LGA036, LGA042, LGA048, LGA060, LGA072, LGA090, LGA102, LGA120, LGA150)
• Lennox S-Class (Suffixes: SGA036, SGA060, SGA090, SGA120)
• Lennox Landmark (Suffixes: LEA036, LEA048, LEA060)
• Lennox GCS Series (Suffixes: GCS24, GCS16 - check serial range)