LiftMaster K20-3100C-4 FDC Motor, 1023/1043
The LiftMaster K20-3100C-4 FDC motor is a specialty commercial replacement motor associated with FDC 1023 and 1043 fire-door / speed-jack operator service references. Unlike the more common GH, GSD, GT, J, H, or T replacement motors, this item is tied to a specific fire-door or speed-operator application path. That matters because fire-door operators can include special release, closing, and code-compliance functions that depend on the correct motor, controls, braking, and operator configuration. The K20-3100C-4 part number should be matched directly to the original motor label or the FDC operator parts diagram. Do not choose a similar 1 HP motor only because the horsepower or voltage appears close. Suffixes such as -4, -4T, and -4P can point to different service paths, and the wrong motor can create control, mounting, or safety issues.
Compatible With / Common Applications
- Select LiftMaster FDC 1023 fire-door / speed-jack commercial operator applications when the diagram lists K20-3100C-4.
- Select LiftMaster FDC 1043 fire-door / speed-jack commercial operator applications when the diagram lists K20-3100C-4.
- Used with various LiftMaster speed jack commercial door operators and fire door operators by exact parts diagram verification.
- Not a general substitute for K20-3100C-4T, K20-3100C-4P, GH1023/GH1043 standard operator motors, or other 1 HP commercial motors.
- Verify operator model, voltage, phase, control type, motor label, release function, and fire-door requirements before ordering.
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster |
| Product Type | FDC / speed operator replacement motor |
| Part Number | K20-3100C-4 |
| Application | FDC, speed jack, and fire door operator motor repair |
| Compatible Operator Type | Select LiftMaster FDC 1023 and 1043 style operator applications by parts diagram |
| Voltage / Phase | Verify by existing motor nameplate and operator diagram |
| Horsepower | Verify by existing motor nameplate and operator diagram |
| Notes | Do not substitute by horsepower alone; fire-door operator applications are configuration-sensitive |
Also Known As / Related Part Numbers
- K20-3100C-4
- LM-K20-3100C-4
- 20-3100C-4
- OCMLM-K20-3100C-4
- LiftMaster FDC Motor 1023 1043
- FDC 1023 Motor
- FDC 1043 Motor
- Speed Jack Motor
- Fire Door Operator Motor
Technician Note
This is the most application-sensitive motor in the batch. Treat it as an FDC/fire-door/speed-operator motor and confirm the exact service diagram. Do not merge it with standard K20-3100C-4T gear-reduced commercial operator motor listings.
Before Ordering Checklist
- Confirm the operator is an FDC, speed jack, or fire-door operator.
- Confirm the model reference is 1023, 1043, or another diagram-confirmed application for K20-3100C-4.
- Compare the original motor nameplate, wiring, mounting, shaft, and part number.
- Review fire-door release and closing functions after repair.
- Arrange code-required inspection or testing where applicable.
Professional Advisory
Fire-door and speed-operator repairs can affect life-safety operation. A qualified commercial door technician should service the operator, verify the motor match, and test the complete fire-door system according to applicable requirements after repair.
Product Questions & Answers
No. Do not assume those are interchangeable. K20-3100C-4 is tied to FDC 1023/1043 fire-door or speed-operator references, while K20-3100C-4T is a different commercial motor path.
What operators is this motor commonly associated with?
It is commonly associated with LiftMaster FDC 1023 and 1043 fire-door / speed-jack operator applications when the diagram lists K20-3100C-4.
Can this be used on a standard GH operator?
Not unless the exact GH parts diagram calls for this part number. The visible FDC 1023/1043 reference should be treated as a separate application path.
Why is fire-door compatibility important?
Fire-door operators can have release and closing functions tied to life-safety requirements. The wrong motor or configuration can interfere with proper system operation.
What should be tested after installation?
The operator should be tested for correct motor operation, direction, limits, release function, fire-door closing behavior, and any code-required safety checks.
