LiftMaster K03-8224-D 24V D-Line Contactor Replacement Kit for Commercial Operator Electrical Boxes

LiftMaster K03-8224-D 24V D-Line Contactor Replacement Kit for Commercial Operator Electrical Boxes

The LiftMaster K03-8224-D is a 24V D-Line contactor replacement kit for select LiftMaster commercial door operator electrical boxes. A contactor is the heavy-duty switching device that allows the operator control circuit to energize motor or direction circuits under load. When a contactor is worn, pitted, stuck, or has a failed coil, the operator may fail to start, chatter, hum, run inconsistently, or show direction-control problems.

This part is commonly described as a contactor replacement kit for various LiftMaster commercial door operator electrical boxes and is also referenced as 03-8224-D. It should be ordered by the exact electrical-box parts diagram, not just by operator brand. LiftMaster uses multiple contactor and reversing-contactor assemblies that can look similar but differ by coil voltage, contact configuration, mounting, and wiring layout.

K03-8224-D should be treated as a commercial motor-control service part. Before replacing it, the technician should check control voltage, terminals, overloads, interlocks, stop circuit, limit circuit, and motor wiring. A failed contactor can be the result of a separate electrical problem, so replacing the contactor without checking the rest of the circuit may not solve the issue.

Compatible With

This part may be used with select LiftMaster commercial door operator electrical boxes that specifically call for the K03-8224-D / 03-8224-D 24V D-Line contactor.

• Select LiftMaster commercial door operator electrical boxes where the parts diagram lists K03-8224-D
• Commercial operator motor-control assemblies requiring a 24V D-Line contactor with this part number
• Select commercial door operator service applications using related number 03-8224-D
• Not a generic relay, not a universal contactor, and not automatically interchangeable with K03-8024-D or other LiftMaster contactor kits
• Use only where the coil voltage, contact arrangement, mounting, and wiring match the original electrical box

Features & Specifications

Also Known As / Related Part Numbers

• K03-8224-D
• 03-8224-D
• LiftMaster K03-8224-D contactor
• LiftMaster 24V D-Line contactor
• K03-8224-D contactor replacement kit

Technician Note

A contactor failure may be caused by a weak control circuit, loose wiring, overload issues, motor faults, or water damage in the electrical box. Inspect the electrical box before replacing the contactor.

Before Ordering Checklist

• Confirm the electrical box parts diagram lists K03-8224-D
• Match the 24V coil/control circuit
• Compare the contact layout, terminals, mounting, and wiring to the old contactor
• Inspect overloads, limits, stop circuit, interlocks, motor wiring, and control-board outputs
• Use a qualified technician for live-voltage testing and commercial operator electrical repair

Professional Advisory

Commercial operator electrical boxes contain line voltage and motor-control components. Do not bypass a contactor, overload, stop circuit, limit circuit, or safety device to keep an operator running. Repair the electrical fault correctly before returning the operator to service.

Product Questions & Answers

What is the K03-8224-D contactor used for?

It is a 24V D-Line contactor replacement kit for select LiftMaster commercial door operator electrical boxes.

Is K03-8224-D the same as 03-8224-D?

03-8224-D is a commonly listed related number for K03-8224-D.

Can this replace any LiftMaster contactor?

No. The coil voltage, contact arrangement, mounting, and wiring must match the operator electrical box parts diagram.

What symptoms can point to a bad contactor?

A worn or failed contactor may cause chattering, failure to start, intermittent operation, stuck contacts, or motor-control problems.

Should this be installed by a technician?

Yes. Contactor replacement involves commercial operator electrical circuits and should be handled by a qualified technician.