920915 Furnace Control Circuit Board User Manual

Introduction

This manual provides comprehensive instructions for the installation, operation, and maintenance of the sixcow 920915 Furnace Control Circuit Board. This board is a direct replacement part designed for single-stage gas furnaces, ensuring precise temperature control, efficient fan operation, and robust system diagnostics. It is engineered to meet or exceed OEM standards for reliability and durability.

Figure 1: The 920915 Furnace Control Circuit Board.

Safety Information

WARNING: RISK OF ELECTRICAL SHOCK. Always shut off all electrical power to the furnace unit before performing any maintenance or service on the system. Failure to follow this warning can cause serious injury, fire, or electrical shock, and may result in death.

• Ensure power is completely off at the circuit breaker or fuse box before beginning installation.
• Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous operation.
• Verify proper operation after servicing.
• Avoid static electricity discharge. Consult a professional if you are not knowledgeable about electricity and gas.
• This product should only be installed by a qualified technician.

Figure 2: Safety warning regarding electrical shock.

Compatibility

The 920915 Furnace Control Circuit Board is designed as a replacement part for a wide range of single-stage gas furnaces. It is compatible with various models from Nordyne, Miller, Intertherm, Gibson, Tappan, Broan, and Frigidaire.

This board is suitable for G7 and M7 furnace models. It can also replace a single-stage G6/L1 control board (part # 624631) with a G7 control board (part # 624690).

Replaces OEM Part Numbers:

• 920915
• 277820
• 624742
• 904840

Compatible Furnace Models (starting with):

• CMF95, FG7SA, FG7SC, FG7SD, FG7SK, FG7SL, FG7SM
• G7XA, G7XC
• KG7SA, KG7SC, KG7SD, KG7SK, KG7SL, KG7SM
• M4RC, M4RL, M7RL
• RG7D
• VG7SA, VG7SC, VG7SD, VG7SK, VG7SL, VG7SM
• MGC2S and more.

Note: Model numbers indicate series/type and features (e.g., M7RL 080A BW means M7RL series, 80,000 BTUs, with specific features). Always check your furnace label for the exact model number to ensure compatibility.

Figure 3: Compatibility information for furnace models.

Product Specifications

The 920915 Furnace Control Circuit Board is manufactured with premium PCB materials, featuring clear circuitry and precise soldering for optimal performance. Its robust structure includes anti-oxidation treatment to withstand high temperatures, ensuring long-lasting use, safety, and stability with over-voltage protection.

Figure 4: Product dimensions and key features.

Installation Procedure

This section outlines the steps to properly replace a single-stage G6/L1 control board with a G7 control board. Clear labeling on the board ensures easy installation and maintenance.

1. Power Disconnection: Before starting, ensure the power to the furnace is completely off at the circuit breaker or fuse box.
2. Document Existing Wiring: Capture detailed photos of your existing board with all wiring connections intact. This is crucial for a seamless transition.
3. Remove Old Board: Carefully disconnect all wires from the old G6/L1 control board. Note the specific pin locations from which they were removed.
4. Wire Transfer (L1 Terminal): The wire that was attached to the L1 terminal on the G6 control board will need to be attached to the L1 terminal on the G7 control board.
5. Wire Transfer (XFMR Terminal): The wire from the XFMR terminal of the G6/L1 board should be placed on the XFMR terminal of the G7 board.
6. Wire Transfer (Thermostat, Heat Pump, AC Unit, Air Handler): When connecting the wires from the thermostat, heat pump, AC unit, or air handler to the RCGYW terminals of the G7 board, install all wires on the same terminals they were removed from.
7. Wire Transfer (Blower Motor): When connecting the wires from the blower motor, note which wire connects to the HEAT and COOL terminals on the G7 control board. Refer to Table 1 for guidance.

   Note: If the motor does not have an orange wire, do not place any wire on the Medium Low terminal; this should be left empty.

8. P1 and P2 Wire Plugs: The 6 pin (P1) and the 9 pin (P2) wire plugs will connect directly to the G7 control board; there is no need to change any wire position.
9. Secure New Board: Install the new 920915 G7 control board securely in place.
10. Restore Power: Once all connections are verified and the board is secured, restore power to the furnace.
11. Verify Operation: Test the furnace to ensure proper operation.
12. Label for Future Reference: Place label with flash codes near the wiring diagram on the furnace door for future reference.

Wiring Diagram and Board Chart

Refer to the following table and diagrams for detailed wiring information.

Figure 5: Installation instructions with wire chart and diagrams.

Figure 6: Detailed wiring diagrams for G6/L1 and G7 control boards.

Operation

The 920915 Furnace Control Circuit Board is designed to automatically manage the furnace's operations, including ignition, flame sensing, fan control, and safety shutdowns. Once properly installed, the board continuously monitors system parameters to ensure efficient and safe heating.

• Ignition Sequence: Initiates the ignition process when a call for heat is received from the thermostat.
• Flame Sensing: Monitors the presence of a flame to ensure safe combustion.
• Fan Operation: Controls the blower fan based on heating and cooling demands.
• System Diagnostics: Provides diagnostic codes (often via LED indicators on the board) to assist in troubleshooting. Refer to your furnace's specific manual for a list of diagnostic codes.

Maintenance

The 920915 Furnace Control Circuit Board requires minimal maintenance itself. However, regular maintenance of your furnace system is crucial for the longevity and optimal performance of all components, including the control board.

• Annual Furnace Inspection: Have your furnace inspected annually by a qualified HVAC technician. This ensures all components, including the control board, are functioning correctly and safely.
• Air Filter Replacement: Regularly replace or clean your furnace's air filter as recommended by the furnace manufacturer. A dirty filter can restrict airflow, causing the furnace to overwork and potentially stress electrical components.
• Clear Vents: Ensure all furnace vents and returns are unobstructed to maintain proper airflow.
• Keep Area Clear: Keep the area around the furnace clear of debris and flammable materials.

Troubleshooting

If your furnace is experiencing issues after installing the 920915 control board, consider the following common troubleshooting steps. Always ensure power is off before inspecting components.

• No Heat/Furnace Not Starting:
  • Check if the thermostat is set to "Heat" and the temperature is above the ambient room temperature.
  • Verify that the furnace's power switch is on.
  • Inspect the circuit breaker for the furnace; reset if tripped.
  • Ensure all wiring connections to the control board are secure and correctly placed according to the wiring diagram.
  • Check the furnace's igniter for proper operation.
• Fan Not Operating Correctly:
  • Ensure the fan setting on the thermostat is correct (e.g., "Auto" or "On").
  • Check the fan motor connections to the control board.
  • Inspect the fan capacitor if the fan hums but doesn't spin.
• Diagnostic Codes (LED Flashes):

  The control board may have an LED light that flashes in specific patterns to indicate error codes. Refer to your furnace's original manufacturer manual or the wiring diagram on the furnace door for a list of these diagnostic codes and their meanings. Common issues indicated by codes include:

  • Pressure switch errors
  • Limit switch errors
  • Flame sensor issues
  • Ignition lockout
• Overheating/Short Circuits: The board is designed with over-voltage protection. If the furnace repeatedly shuts down due to overheating, check for blocked vents, dirty filters, or issues with the limit switch.

If troubleshooting steps do not resolve the issue, it is recommended to contact a qualified HVAC technician for further diagnosis and repair.

Warranty and Support

Warranty: All sixcow products, including the 920915 Furnace Control Circuit Board, come with a 30-Day money-back guarantee and a 12-Month warranty for quality-related issues. For warranty claims, simply return the product.

Customer Support: For any questions, technical assistance, or warranty inquiries, please contact sixcow customer service. Your satisfaction is our priority, and we strive to provide excellent service.

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