What to do with extra line set on MRCOOL & other mini split AC units

A line set is a pair of copper pipes that connect the indoor and outdoor units of ductless mini-split air conditioning and heating systems. They transport refrigerant between the evaporator inside and the condenser outside.

When you install a mini-split system like the popular MRCOOL brand, you’ll likely end up with extra line set length. You’ll need to be very careful when handling this excess tubing so it works correctly and doesn’t get damaged. If the extra line set isn’t installed correctly, your unit may have reduced efficiency, leaks or tangles of line.

Let’s walk through the key steps for dealing with spare line set length on a MRCOOL or other mini-split AC system. 

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Disclaimer: The information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

Why proper line set handling is important

It may be tempting to hastily stuff any leftover line set length into random coils or loops, but taking the time to properly run and secure excess tubing makes a big difference. 

Here’s what can happen if you handle the line set incorrectly:

• Kinks, twists, or tight bends in the line set restrict refrigerant flow. This starves the evaporator and condenser of adequate refrigerant and reduces the unit’s cooling/heating capacity.

• Excess vibration or movement can stress the connections and introduce refrigerant leaks.

• An improperly secured line set has a higher likelihood of punctures, cracks, breaks, rodent damage, or rubbing that can degrade the tubing over time.
  
  

How to deal with extra line set

Step 1 – Trim (if needed)

If the excess line set length is very long (more than 10 feet), trimming and re-flaring it shorter may help you coil it better.

You can use a tubing cutter to trim the line set squarely, then re-flare the ends with a flaring tool kit.

For extra line set that’s 10 feet long and under, neatly coiling the tubing is the preferred method.

Step 2 – Coil

1. Neatly coil any excess line set into evenly-sized loops near the outdoor condenser unit. Make sure to leave about 3 to 5 inches of slack to allow space for minor vibration, shifting, or repositioning of the condenser.
2. Check for any kinks and twists. Avoid sharp 90° kinks that can severely restrict refrigerant flow and don’t overtwist the tubing, which can block flow within the line.
3. Use a plastic line set cover or cable ties spaced every 8 to 12 inches to bundle the tubing loops together. This prevents sagging, maintains coil shape, and keeps the line set off the ground.

Step 3 – Elevate

1. Place the coiled line set on a small platform or mounting bracket to keep it elevated off the ground. A plastic or metal platform or mounting brackets work well for supporting line set coils. 
2. Secure the line set with cable ties.
   

Keeping the line set coil elevated prevents:

• Corrosion and rust damage from moisture, dirt, leaves, etc.

• Accidental kicks and damage from lawn mowers or string trimmers

• Direct contact with wet, muddy, or flooded ground
  

Step 4 – Insulate

Use line set insulation to cover any exposed portions of copper line set. Outdoor UV-resistant foam line set insulation works well. You can secure it with cable ties or vinyl tape.

Insulation protects the line from exposure to damaging outdoor elements such as direct sun exposure, rain, hail and strong winds. It also prevents condensation from forming and dripping on the line set.

More information

You made it! We hope this guide helped you learn how to safely handle the extra line set for your mini split AC unit.

If you have any other appliance repair needs or projects, don’t hesitate to explore our other troubleshooting guides and videos. 

If you need replacement parts or some extra help with ordering them, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, read our DIY blog and more.

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