Two Frameworks, One Technician
As of January 1, 2026, HVAC technicians in the United States operate under two distinct EPA regulatory frameworks. Section 608 of the Clean Air Act continues to govern ozone-depleting substance (ODS) refrigerants like R-22. Alongside it, Subpart C of the AIM Act (40 CFR Part 84, Subpart C) now imposes leak repair requirements on hydrofluorocarbon (HFC) refrigerants – the very substances that replaced the ODS chemicals being phased out.
For solo technicians, this means knowing which set of rules applies to every system you touch. The answer depends on the refrigerant type and its global warming potential (GWP).
Which Framework Applies?
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Section 608 applies to systems containing ODS refrigerants (Class I and Class II substances) with a full charge of 50 pounds or more. Common examples: R-22, R-12, R-502, R-123.
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Subpart C applies to systems containing HFC or HFC-blend refrigerants with a GWP greater than 53 and a full charge of 15 pounds or more. This covers R-410A (GWP 2,088), R-134a (GWP 1,430), R-407C (GWP 1,774), and newer A2L alternatives like R-454B (GWP 466).
Refrigerants with a GWP of 53 or below – such as R-290 (propane, GWP 3) and R-744 (CO2, GWP 1) – are not subject to Subpart C leak repair requirements.
If you retrofit a system from an ODS refrigerant to an HFC refrigerant, it transitions to the Subpart C framework once the new refrigerant is installed.
Side-by-Side Comparison
| Requirement | Section 608 (ODS) | Subpart C (HFC, GWP > 53) |
|---|---|---|
| Charge threshold | 50 lbs | 15 lbs |
| Commercial refrigeration leak rate | 20% | 20% |
| Comfort cooling leak rate | 15% | 10% |
| Industrial process leak rate | 30% | 30% |
| Refrigerated transport leak rate | N/A | 10% |
| Repair deadline (commercial/comfort) | 30 days | 30 days |
| Repair deadline (industrial) | 120 days | 120 days |
| Initial verification test | At repair completion | At repair completion |
| Follow-up verification window | 30 days | 10 days |
| Record retention | 3 years | 3 years |
| Chronic leaker threshold | N/A | 125% annual leak rate |
Key Differences Explained
1. Lower Charge Threshold (15 lbs vs 50 lbs)
This is the single most impactful change. Under Section 608, only systems with 50+ pounds triggered leak repair requirements. Subpart C drops that to 15 pounds, bringing a massive number of smaller commercial systems into regulation. A standard 5-ton commercial rooftop unit with R-410A typically holds 15 to 25 pounds, meaning it now falls under full leak repair tracking.
For solo techs, this means more systems require formal leak rate calculations, more repair deadlines to track, and more records to maintain.
2. Tighter Comfort Cooling Threshold (10% vs 15%)
Section 608 set comfort cooling at 15%. Subpart C tightens it to 10%. This category encompasses the largest segment of equipment most solo technicians service: commercial air conditioners, heat pumps, and ductless mini-splits above the 15-pound charge minimum.
A 10% threshold means a system with a 20-pound charge that loses just 2 pounds over a year is already at the limit. Systems compliant under the old 15% standard may now trigger repair obligations.
3. New Refrigerated Transport Category (10%)
Section 608 had no specific transport category. Subpart C adds refrigerated transport with a 10% leak rate threshold, covering transport refrigeration units (TRUs) on trucks, trailers, shipping containers, and rail cars using HFC refrigerants above 15 pounds. If you service TRUs, this is an entirely new compliance obligation.
4. Shorter Follow-Up Verification Window (10 days vs 30 days)
Both frameworks require an initial verification test at repair completion. The difference is in the follow-up: Section 608 allows 30 days, while Subpart C shortens it to 10 days.
For solo technicians, this compressed timeline means scheduling return visits much sooner. Missing the 10-day window puts you out of compliance even if the repair itself was successful.
5. Chronic Leaker Reporting (125% Annual Leak Rate)
Subpart C introduces the chronic leaker concept – equipment that has leaked refrigerant equal to or exceeding 125% of its full charge over a rolling 12-month period. This triggers additional reporting obligations and may require the equipment owner to develop a retrofit or retirement plan. Section 608 has no equivalent designation.
Practical Implications for Solo Technicians
Identifying the Framework in the Field
When you arrive at a job site:
- Identify the refrigerant from the equipment nameplate or service records.
- Check the GWP. ODS refrigerants fall under Section 608. HFCs with GWP above 53 fall under Subpart C.
- Determine the full charge. If it meets or exceeds the applicable threshold (50 lbs for Section 608, 15 lbs for Subpart C), full leak repair tracking is required.
Servicing Mixed Fleets
Many solo technicians service both older ODS systems and newer HFC equipment in a single day. You must apply the correct framework to each system independently. There is no blending or averaging across systems.
Increased Documentation Burden
The lower Subpart C charge threshold significantly increases the number of systems requiring formal documentation. Where Section 608 only required tracking for larger commercial systems, Subpart C pulls in many smaller units. Solo technicians need an efficient system for recording refrigerant additions, calculating leak rates, and tracking repair deadlines across a larger fleet of regulated appliances.
How FieldPad Handles Dual-Framework Compliance
FieldPad automatically detects the applicable regulatory framework based on refrigerant type and GWP when you log a service event:
- ODS refrigerants are routed to Section 608 thresholds and deadlines.
- HFC refrigerants with GWP above 53 are routed to Subpart C thresholds and deadlines.
- Low-GWP refrigerants (GWP 53 or below) are flagged as exempt from leak repair tracking.
FieldPad applies the correct leak rate thresholds (including the tighter 10% comfort cooling threshold under Subpart C), sets the appropriate follow-up verification window (10 days vs 30 days), and monitors for chronic leaker status on HFC equipment. For solo technicians managing dozens of systems across both frameworks, this automated detection eliminates one of the most common sources of compliance errors: applying the wrong threshold to the wrong system.
Key Takeaways
- Two frameworks now coexist: Section 608 for ODS refrigerants and Subpart C for HFC refrigerants with GWP above 53, effective January 1, 2026.
- Subpart C has a much lower charge threshold (15 lbs vs 50 lbs), bringing many more systems under formal leak repair requirements.
- Comfort cooling threshold is tighter under Subpart C (10% vs 15%), meaning smaller leaks now trigger repair obligations.
- Follow-up verification tests must happen within 10 days under Subpart C, not 30 days as under Section 608.
- Refrigerated transport is a new appliance category under Subpart C with a 10% leak rate threshold.
- Chronic leaker tracking (125% annual leak rate) is a Subpart C requirement with no Section 608 equivalent.
- FieldPad auto-detects the applicable framework based on refrigerant GWP, applying the correct thresholds, deadlines, and verification windows automatically.
Sources & Regulatory References
- 40 CFR Part 82, Subpart F — Section 608 leak repair regulations for ODS refrigerants
- 40 CFR Part 84 — AIM Act regulations including Subpart C HFC leak repair requirements
- EPA Section 608 — EPA’s Section 608 regulatory page
- EPA AIM Act — HFC Phasedown — EPA’s overview of HFC reduction under the AIM Act
