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White Rodgers 50M56U-751 - User Manual

White Rodgers 50M56U-751
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The 50M56U-751 kit is a Single Stage HSI Integrated Furnace
Control kit for Carrier. This kit replaces the following Carrier
controls:
Carrier White-Rodgers
HK42FZ004 HK42FZ009 HK42FZ016 50M56-751
HK42FZ007 HK42FZ011 HK42FZ034
HK42FZ008 HK42FZ013 325878-751*
*Universal replacement for all Carrier controls.
The control employs a microprocessor to continually monitor,
analyze, and control the proper operation of the gas burner,
inducer, and fan.
Twinning: The control board in this Kit CANNOT be
twinned with any of the Carrier circuit boards.
50M56U-751
Carrier Single Stage
HSI Integrated Furnace Control Kit
INSTALLATION INSTRUCTIONS
DESCRIPTION
Installation should be done by a qualified heating and air
conditioning contractor or licensed electrician.
If in doubt about whether your wiring is millivolt, line, or low
voltage, have it inspected by a qualified heating and air
conditioning contractor or licensed electrician.
Do not exceed the specification ratings.
All wiring must conform to local and national electrical codes
and ordinances.
This control is a precision instrument, and should be handled
carefully. Rough handling or distorting components could
cause the control to malfunction.
Following installation or replacement, follow manufacturer’s
recommended installation/service instructions to ensure
proper operation.
PRECAUTIONS
Do not short out terminals on gas valve or primary
control. Short or incorrect wiring may damage the
thermostat.
CAUTION
!
Failure to comply with the following warnings could result
in personal injury or property damage.
FIRE HAZARD
• Do not exceed the specified voltage.
• Replace existing control with exact model and
dash number.
• Protect the control from direct contact with water
(dripping, spraying, rain, etc.).
• If the control has been in direct contact with
water, replace the control.
• Label all wires before disconnection when
servicing controls. Wiring errors can cause
improper and dangerous operation.
• Route and secure wiring away from flame.
SHOCK HAZARD
• Disconnect electric power before servicing.
• Ensure proper earth grounding of appliance.
• Ensure proper connection of line neutral and line
hot wires.
EXPLOSION HAZARD
• Shut off main gas to appliance until installation
is complete.
WARNING
!
FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL
INJURY AND/OR PROPERTY DAMAGE.
PART NO. 37-7513C
Replaces 37-7513B
1611
white-rodgers.com
emersonclimate.com
50M56-751
The kit contains:
1 – 50M56-751 ignition control board
1 – Set of interconnect harnesses
1 – Manual
1 – Bag of accessories

Table of Contents

Questions and Answers

  • K
    Katelyn FaulknerAug 13, 2025
    How to fix external lockout (exceeded retries) on White Rodgers 50M56U-751?
    • A
      Amy MillerAug 14, 2025
      If the White Rodgers Controller experiences an external lockout due to exceeded retries, it's often caused by a failure to sense the flame. This can be due to carbon deposits on the flame sensor, a disconnected or shorted flame sensor lead, or a poorly grounded furnace. Try cleaning any carbon deposits with emery cloth. Make sure the sensor isn't touching the burner and is well-positioned to sense the flame. Inspect the sensor lead for shorts and ensure the furnace is properly grounded. Also, check the gas supply to the valve, confirm the gas valve is in the "On" position, and verify the appliance is lighting correctly. Ensure the flame reaches the flame sensor during ignition attempts and that gas pressures are correct.
  • J
    jonespatriciaAug 17, 2025
    Why is the flame sense current low on my White Rodgers 50M56U-751?
    • S
      Shelly RiveraAug 17, 2025
      Low flame sense current in a White Rodgers Controller is often due to carbon deposits on the flame sensor, a poorly grounded furnace, or a mis-aligned flame sense probe. To resolve this, clean any carbon deposits from the flame sensor using emery cloth. Check and improve the grounding of both the furnace and the module. Make sure the sensor is located in or very near the flame as the appliance manufacturer specifies. Refer to the wiring diagram for the FS terminal and GND.
  • E
    Eric GrayAug 21, 2025
    What to do if White Rodgers 50M56U-751 Controller has reversed polarity?
    • A
      Andre BallardAug 21, 2025
      If you suspect reversed polarity with your White Rodgers Controller, verify that both the control and the furnace are properly grounded. Check the polarity (primary or secondary) and reverse it if it's incorrect.
  • S
    Sherri JohnsonAug 25, 2025
    Why is flame sensed when gas valve is de-energized in White Rodgers 50M56U-751 Controller?
    • G
      Gregory SparksAug 26, 2025
      To address a situation where flame is sensed with the gas valve de-energized or the rollout switch is open on your White Rodgers Controller, verify that the gas valve is operating and shutting down properly. The flame in the burner assembly should extinguish promptly at the end of the cycle. Also, check the orifices and gas pressure.
  • G
    gregbrewerAug 28, 2025
    What to do if pressure switch is stuck open on White Rodgers Controller?
    • W
      William SellersAug 29, 2025
      To troubleshoot a pressure switch stuck open on your White Rodgers Controller, check the pressure switch function and tubing. Verify the inducer is turning on and pulling sufficient vacuum to engage the switch. Refer to the wiring diagram, terminals PSI / PSO. Also check low inlet gas pressure (if used).
  • R
    radamsSep 1, 2025
    How to check pressure switch stuck closed on White Rodgers 50M56U-751 Controller?
    • R
      Rebecca HicksSep 1, 2025
      If the pressure switch is stuck closed on your White Rodgers Controller, check the switch function, and verify the inducer is turning off. Refer to the wiring diagram, terminals PSI / PSO.
  • C
    carpenterjustinSep 5, 2025
    How to troubleshoot open high temperature limit switch on White Rodgers Controller?
    • C
      campbellstephanieSep 5, 2025
      To address an open high-temperature limit switch or an open rollout switch in your White Rodgers Controller, verify continuity through the limit switch circuit. Refer to the wiring diagram terminals, HLI / HLO, or check the open rollout switch.
  • J
    Jennifer TerrySep 8, 2025
    How to fix ignitor relay fault on White Rodgers Controller?
    • M
      Michelle HuntSep 8, 2025
      To fix an ignitor relay fault on White Rodgers Controller, replace the ignition module.

Summary

Precautions

Safety Warnings

Critical warnings regarding fire, shock, and explosion hazards during installation and operation.

Installation

Mounting and Wiring Guidelines

Instructions for securing the control and connecting wires according to codes.

Wiring Diagram

Typical System Wiring Diagram

Visual representation of how the 50M56 control connects to system components.

System Lockout and Diagnostics

System Lockout Features

Explains lockout conditions and how to reset the control after a lockout event.

Diagnostic Features

Fault Recall and Reset

Troubleshooting

LED Flash Codes

Maps diagnostic LED flash patterns to specific error conditions and troubleshooting steps.

White Rodgers 50M56U-751 Specifications

General IconGeneral
BrandWhite Rodgers
Model50M56U-751
CategoryController
LanguageEnglish

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