903429A Nordyne Control Board (M Series Units)

Normal Stocking Item 

Replaces: 903429

Product Overview

903429A is a factory-authorized Nordyne replacement control board for M series gas furnaces, providing complete sequencing of inducer, ignition, gas valve, and blower operations in a single plug-and-play module.

Technical Specifications

• Control voltage: 24 VAC

• Board type: Microprocessor-based M series logic

• Status indicators: Multi-color LED for diagnostics and fault codes

• Terminal layout: Clearly labeled screw and push-on connectors for limit switches, thermostat, inducer, gas valve, blower, and flame sensor

• Diagnostic modes: User-accessible test routines via thermostat jumpers

• Mounting: Direct-fit to OEM bracket with pre-drilled mounting holes

• Ambient rating: –40 °F to 140 °F operating temperature

• Dimensions: 6.5 × 4.5 × 1.2 in (approximate)

• Weight: 0.85 lb

Cross-Reference Part Numbers

Compatibility

This control board fits Nordyne M series single- and multi-stage gas furnaces, including but not limited to:

• M1GB/M1GC/M1GD/M1GH series

• M2MA/M2MB/M2MC/M2MD series

• Factory-labeled private-brand M series units

Always verify your furnace model and data-plate part number before ordering.

Technician Notes

1. Disconnect all power sources and shut off the gas supply before servicing.

2. Photograph or label every wiring harness and thermostat connection to ensure accurate reconnection.

3. Remove the old control board from its mounting bracket; inspect harnesses and connectors for damage.

4. Install the new 903429A board onto the bracket, aligning all mounting holes and securing hardware.

5. Reconnect wiring per your reference photos, ensuring tight, corrosion-free terminals.

6. Restore 24 VAC power, then initiate a heat call; observe LED indicators for normal operation (solid green) or diagnostic flash codes.

7. If a fault appears, consult the M series service manual for code definitions and troubleshooting steps.

Additional Resources

• Downloadable M series wiring diagram & installation guide (PDF)

• Printable control board cross-reference cheat sheet

903429 Nordyne integrated control board M Series units

1 year Warranty on everything we sell! 

Nordyne integrated UTECH circuit board for M1M furnaces. For a spare or replacement fuse, order 3A fuse G32-189.

Replaces 624602, 6246020, 624602-0, 624602A, 624602B & 624640, 624640-A

CONTROL LIGHT STATUS
RED
Steady ON Control OK
Steady OFF No power
Rapid Flash False flame or internal control fault
1 Flash Limit switch is open
2 Flashes Pressure switch is open with inducer on
3 Flashes Pressure switch is closed with inducer off
4 Flashes Lockout due to failed ignition
5 Flashes 115 vac & neutral reversed or no ground

YELLOW
Steady ON Good Flame Signal
Blinking Weak Flame Signal
Steady OFF No Flame Signal

M1M-Control Board Replacement
Replace the control board only after determining a failure has occurred in it. Most problems that are blamed on control are actually external to control. If control has failed, use the following procedure to replace.
1. Disconnect power to unit by turning off power switch.
2. Disconnect molex plugs and all push on terminal connections. Note connections for rehook up.
3. After all wire connections have been removed you mustsqueeze the four white stand offs to remove board.
4. Carefully line up holes on the new board over standoffs, and push into place. Caution: push from outside edge only - be careful of fragile components.
5. Reinstall all molex plugs and wires removed in step 2.
6. Apply power and re-test.