Mini Split Line Set Leaking? Class Action Lawsuit Investigation
Last Updated on March 3, 2026
At A Glance
- This Alert Affects:
- Homeowners and property owners who had a mini split HVAC system with a Mueller line set that leaked, as well as HVAC installers/technicians who had to replace the line sets.
- What’s Going On?
- Attorneys believe certain Mueller line sets used in mini split systems may be plagued by a defect that causes the copper tubing to develop pinhole leaks, which can result in the system no longer cooling. They’re looking into whether a lawsuit can be filed against Mueller on behalf of those who had to pay for replacements and damages.
- How Could a Lawsuit Help?
- A lawsuit may be able to help affected individuals recover money for the cost of repairing or replacing the line sets in mini split systems.
- What You Can Do
- If you had a mini split HVAC system installed in the last 10 years with a Mueller line set that failed due to corrosion, or you are an HVAC installer/technician who covered some or all of the cost of repairing or replacing corroded Mueller line sets, fill out the form on this page to help the investigation.
Attorneys working with ClassAction.org are looking into whether a class action lawsuit can be filed over a potential defect in certain line sets used in mini split HVAC systems that could be causing them to fail within only a few years of use.
Specifically, the attorneys are investigating whether certain line sets—i.e., sets of tubing and insulation that connect a mini split’s outdoor condenser to the indoor air handler—manufactured by Mueller are afflicted by a defect that causes the copper tubes to corrode, resulting in pinhole leaks that allow refrigerant to escape and the system to ultimately stop cooling.
The attorneys now want to speak with the following potentially affected individuals as part of their class action lawsuit investigation into the potential Mueller line set defect:
- Homeowners or property owners who had a mini split system with a Mueller line set installed in the last 10 years and either had to replace the line set, had to recharge the refrigerant or stopped using their mini split system due to corrosion of the line set
- HVAC technicians/installers who had to replace Mueller line sets in mini split systems due to pinhole corrosion and incurred damages as a result
To help the investigation into mini split line set leaks, fill out the form on this page and an attorney or legal representative may reach out to you directly to explain more.
What Could Be Causing Mini Split Line Set Leaks?
Some HVAC technicians have hypothesized that mini split line set corrosion could be caused by a chemical reaction between moisture and the insulation surrounding the copper tubing, which results in an acidic environment that corrodes the copper. According to HVAC professionals, formicary corrosion in line sets—i.e., when an organic acid degrades the copper in the tubing—can show up as green or black spots on copper lines and results in pinhole leaks under insulation in mini split systems. Pinhole leaks in HVAC line sets cause refrigerant to escape from the system, hindering its ability to cool properly.
Many HVAC professionals have observed formicary corrosion in white insulated HVAC lines, but some techs have noted pinhole leaks in line sets with other types of insulation as well.
Complaints About Mini Split Line Set Leaks, Corrosion
Homeowners and HVAC installers alike have turned to online forums such as Reddit to post complaints about copper line set corrosion and refrigerant leaks in mini split systems.
Some consumers said they experienced multiple instances of mini split line set leaks due to corrosion, with the new line sets developing pinhole leaks within only a few years. Those who paid out of pocket to have their line sets replaced said they were on the hook for hundreds or thousands of dollars, and one consumer complained about having to pay for “what seems to be a known product defect” despite having a 12-year parts warranty from the mini split manufacturer.
HVAC installers and technicians have also posted complaints about HVAC line set pinhole leaks, claiming that in many cases, they (or the company they work for) had to foot the bill for replacing corroded line sets.
How Could a Mueller Line Set Class Action Lawsuit Help?
If filed and successful, a lawsuit could help affected homeowners, property owners or HVAC installers/technicians recover money for any damages they may have incurred due to mini split line set corrosion, which could include the costs of initially buying a defective product, replacing corroded line sets and/or purchasing a replacement HVAC system.
Had an HVAC Line Leak? Take Action
If you are a homeowner, property owner or HVAC installer/technician who incurred damages due to the corrosion of Mueller line sets in mini split HVAC systems, fill out the form on this page.
After you get in touch, an attorney or legal representative may reach out to you directly to ask you some questions about your experience and explain how you may be able to help the investigation into the potential Mueller mini split defect. It doesn’t cost anything to fill out the form or speak with someone, and you’re not obligated to take legal action.
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