MRCOOL 5th Gen Coupler Kit DIYCOUPLER-58 + DIYCOUPLER-38 + 75ft MC-5 Cable

MRCOOL 5th Gen Coupler Kit DIYCOUPLER-58 + DIYCOUPLER-38 + 75ft MC-5 Cable

The MRCOOL 5th Gen DIY Coupler Kit with 3/8″ and 5/8″ Couplers and 75 ft MC‑5 Communication Cable is a practical accessory for extending MRCOOL DIY Quick Connect® mini‑split refrigeration lines. When a single pre‑charged line set isn’t long enough to span the distance between your indoor air handler and outdoor condenser, this kit allows you to seamlessly join two existing line sets to create a longer, continuous run while maintaining system integrity and performance.

This kit includes both a 3/8″ liquid line coupler and a 5/8″ suction (gas) line coupler, making it compatible with standard MRCOOL DIY 5th Gen line set sizes. The dual coupler design ensures a secure, leak-resistant connection between combined line segments, so you can extend your setup without compromising refrigerant seal or system efficiency.

In addition to the line couplers, the kit comes with a 75‑foot MC‑5 communication cable, providing generous length to connect indoor and outdoor components even when they’re placed far apart — ideal for larger homes, detached structures, or custom layouts that require extra flexibility. This extended wiring supports uninterrupted signal and control between system components.

Designed with DIY-friendly installation in mind, the couplers and cable fit MRCOOL Quick Connect® technology, eliminating the need for vacuum pumps, brazing, or specialized tools. Whether customizing your HVAC layout or accommodating placement challenges, this coupler kit provides a reliable way to expand your MRCOOL DIY mini‑split system.

Features

• Easy Line Extension – Join two standard Quick Connect® Line Sets to create a longer, seamless connection.
  
• Dual Coupler Compatibility – Includes both 3/8" liquid line and 5/8" gas line couplers.
  
• Designed for DIY Installation – Tool-free connections make this a fast and reliable extension solution.
  
• Heavy-Duty Insulation – Ensures minimal refrigerant loss and optimized system performance.
  
• 75 Ft. Communication Cable – Extended cable allows flexible placement of indoor and outdoor units.

Specifications

Applications

• Extended Line Set Installations – Great for homes with outdoor units placed farther from the air handler.

• Custom DIY Projects – Useful when designing a system layout for unique architectural conditions.

• Retrofits & Renovations – Simplifies rerouting line sets around additions or newly built rooms.

• Garage and Basement Solutions – Easily accommodates units mounted in hard-to-reach or external areas.

• Multi-Room Configurations – Supports configurations needing greater installation flexibility.

What’s Included

• 1 × 3/8" Liquid Line Coupler

• 1 × 5/8" Gas Line Coupler

• Insulation

• 1 × 75 Ft. MC-5 Communication Cable

Frequently-Asked Questions

Can this kit be used with smaller air handlers like 12K or 18K?
No. This coupler kit is specifically designed for 24K and 36K air handlers. For smaller systems, refer to MRCOOL's compatible line extension kits.

Do I need a vacuum pump or special tools for this installation?
No. This is a true DIY-friendly kit—the Quick Connect® system means no vacuuming or brazing is needed.

Will this impact system performance?
Not if installed properly. The insulated couplers and factory-sealed connections ensure minimal loss and maintain system efficiency.

Is the communication cable pre-attached?
No. The 75 ft. communication cable comes separately and needs to be wired to your system during installation.

Manual

• Installation Manual