Section 608 vs. the AIM Act: What Actually Changed for Refrigerant Management in 2026
If you have been in the HVAC industry for any length of time, Section 608 is second nature. You know the thresholds, you know the requirements, you have been operating under those rules for decades. Then the AIM Act arrived, and the question most experienced contractors are asking is straightforward: what is actually different, and do I need to change how I operate?
The short answer is yes — substantially. The AIM Act’s Subpart C is not a minor update to Section 608. It is a parallel regulatory framework that covers different refrigerants, applies to smaller systems, imposes tighter thresholds, and introduces entirely new obligations. And Section 608 does not go away. You now comply with both.
This article provides a definitive side-by-side comparison so you know exactly where the requirements overlap, where they diverge, and what changes you need to make in your daily operations.
The fundamental difference
Section 608 and the AIM Act regulate different substances under different parts of the Code of Federal Regulations.
Section 608 lives in 40 CFR Part 82, Subpart F. It regulates ozone-depleting substances (ODS) — specifically CFCs (R-12, R-502) and HCFCs (R-22). These are the legacy refrigerants being phased out under the Montreal Protocol. Section 608 has been in effect since 1993 and is well-understood by the industry.
The AIM Act’s Subpart C lives in 40 CFR Part 84, Subpart C. It regulates hydrofluorocarbon (HFC) refrigerants with a global warming potential above 53. This covers the refrigerants that replaced ODS substances: R-410A, R-404A, R-134a, R-407C, R-507A, and others. Subpart C took effect January 1, 2026.
The two regulations operate in parallel. A contractor who services R-22 systems and R-410A systems must apply Section 608 requirements to the R-22 systems and Subpart C requirements to the R-410A systems. They are not interchangeable.
Side-by-side comparison
System size threshold
Section 608: 50 pounds of ODS refrigerant. Systems below 50 pounds are not subject to leak repair requirements.
AIM Act Subpart C: 15 pounds of HFC refrigerant (GWP > 53). Systems below 15 pounds are exempt.
What this means: The AIM Act brought a massive number of additional systems under federal oversight. A 20-pound rooftop unit using R-410A was unregulated under Section 608 (which only covered ODS anyway) and is now fully regulated under Subpart C. This is the single change with the greatest operational impact for most contractors.
Leak rate thresholds
Section 608:
- Commercial refrigeration: 35%
- Industrial process refrigeration: 35%
- Comfort cooling: 10% (added in 2016 update, effective 2019)
AIM Act Subpart C:
- Commercial refrigeration: 20%
- Industrial process refrigeration: 30%
- Comfort cooling: 10%
What this means: The AIM Act significantly tightened thresholds for commercial and industrial refrigeration. The comfort cooling threshold remains at 10%, matching the 2016 Section 608 update — but now applies to HFC systems as small as 15 pounds. A commercial refrigeration system that was comfortably below the 35% Section 608 threshold may now trigger the 20% Subpart C threshold. Contractors who relied on the generous 608 thresholds for commercial and industrial systems will need to recalibrate their expectations for HFC systems.
When leak rate calculations are required
Section 608: Leak rate should be calculated whenever refrigerant is added to a system exceeding 50 pounds. In practice, many contractors calculated leak rates periodically rather than at every addition.
AIM Act Subpart C: Leak rate must be calculated and documented at every refrigerant addition to a regulated system (15+ pounds). There is no exception for small additions or routine top-offs.
What this means: The documentation burden increased significantly. A system that gets topped off three times a year requires three separate, documented leak rate calculations — each using the correct cumulative total, the correct full charge, and the correct calculation period. This is where manual tracking systems begin to strain.
Repair timeline
Section 608: 30 days to complete a leak repair when the threshold is exceeded. Follow-up verification required.
AIM Act Subpart C: 30 days to complete a leak repair when the threshold is exceeded. Follow-up verification required. If the repair fails, a retrofit or retirement plan must be developed within an additional 6 months.
What this means: The initial repair timeline is identical. The AIM Act adds a more structured escalation path (retrofit/retirement plan) when initial repairs fail, which creates additional documentation requirements.
Documentation requirements
Section 608: Records of refrigerant additions, leak rate calculations, and repairs. Retention for 3 years. Records available upon EPA request.
AIM Act Subpart C: Records of every refrigerant addition (including amount, date, technician, and calculated leak rate), repair records with timelines and verification test results, ALD installation and calibration records, refrigerant source tracking, chronic leaker identification, and annual reporting for systems exceeding 125% of charge. Retention for 3 years. Records available within 5 business days of EPA request.
What this means: Subpart C is substantially more prescriptive about what must be documented and introduces several categories of documentation that have no Section 608 equivalent (ALD records, refrigerant source, chronic leaker reports).
Automatic leak detection
Section 608: No ALD requirement.
AIM Act Subpart C: ALD required for commercial and industrial refrigeration systems with charges of 1,500+ pounds. New systems must have ALD within 30 days of commissioning. Existing systems (2017–2025) must be retrofitted by January 1, 2027. Annual calibration required.
What this means: This is an entirely new obligation with no Section 608 precedent. Contractors servicing large grocery, cold storage, and industrial refrigeration systems must address this requirement for the first time.
Annual reporting
Section 608: No annual reporting requirement for individual contractors or system owners (beyond general record-keeping).
AIM Act Subpart C: Systems that leak 125% or more of their full charge in a calendar year must be reported to EPA by March 1 of the following year.
What this means: Contractors must actively monitor total annual additions to each system and identify chronic leakers. This requires either a year-end review process or, more reliably, continuous tracking that flags systems approaching the 125% threshold throughout the year.
Refrigerant recovery requirements
Section 608: Refrigerant must be recovered before opening a system for service, repair, or disposal. Venting is prohibited. Technicians must use certified recovery equipment.
AIM Act Subpart C: Same core requirements. HFC refrigerant must be recovered, not vented. Additionally, the broader AIM Act phasedown means recovered HFC refrigerant must increasingly be sent for reclamation (cleaning to virgin-specification quality) rather than reused as-is.
What this means: Recovery obligations are functionally the same. The growing emphasis on reclamation rather than simple recovery may affect how contractors handle recovered refrigerant inventory.
Certification requirements
Section 608: Technicians must hold Section 608 certification (Type I, II, III, or Universal) to service refrigerant systems. Certification does not expire but was obtained through an EPA-approved testing program.
AIM Act Subpart C: The same Section 608 certification applies. No additional certification is required under Subpart C. However, technicians must be trained on the different thresholds, documentation requirements, and procedures specific to HFC systems.
What this means: No new certification is needed, but training is essential. A technician who operates under the old Section 608 thresholds when servicing an HFC system will apply the wrong leak rate thresholds and potentially miss required repairs.
Systems with both ODS and HFC refrigerants
Some facilities have equipment using both ODS refrigerants (covered by Section 608) and HFC refrigerants (covered by Subpart C). This is common in facilities that have undergone partial equipment upgrades — older R-22 systems alongside newer R-410A systems.
For these facilities, your compliance program must apply the correct regulation to each system based on its refrigerant type. An R-22 walk-in cooler with a 60-pound charge is regulated under Section 608 with a 35% threshold. An R-404A walk-in cooler with a 45-pound charge at the same facility is regulated under Subpart C with a 20% threshold. Applying the wrong threshold to either system creates compliance risk.
Your equipment inventory should clearly tag each system with its regulatory framework (608 or Subpart C) and apply the corresponding thresholds, documentation requirements, and reporting obligations.
The practical takeaway
If you have been operating under Section 608 for years, you already understand the core concepts: track refrigerant, calculate leak rates, repair leaks within deadlines, keep records. The AIM Act does not change these concepts — it tightens them, expands their scope, and adds new obligations.
The adjustments you must make are specific and non-negotiable. Lower your threshold awareness from 50 pounds to 15 pounds. Apply the stricter leak rate thresholds for commercial (20% instead of 35%) and industrial (30% instead of 35%) systems. Document every refrigerant addition, not just periodic calculations. Track ALD for large systems. Monitor for chronic leakers. And maintain records that can withstand the increased scrutiny that comes with a broader regulatory scope.
RefriComply handles both Section 608 and AIM Act systems in a single platform. Each system is tagged with its regulatory framework, and the correct thresholds and documentation requirements are applied automatically. One system, both regulations, zero confusion.
See How RefriComply Handles Both 608 and AIM Act Compliance →