Regulatory Guide • Reefer Compliance
CARB & Your Reefer Unit: What Every Fleet Operator Running California Needs to Know
CARB's TRU regulation applies to every Carrier Transicold and Thermo King unit operating in California — including yours, even if you're based in Canada. Here's what it requires and what it means for your fleet.
What is CARB — and why does it affect your reefer?
The California Air Resources Board (CARB) is the state agency responsible for regulating vehicle and equipment emissions across California. Most fleet operators know CARB from truck engine regulations, but there's a separate and equally important program that directly targets transport refrigeration units (TRUs) — the Carrier Transicold and Thermo King units mounted on your trailers and straight trucks.
CARB adopted the TRU Airborne Toxic Control Measure (TRU ATCM) in 2004, then significantly amended it in 2022 to tighten emissions standards, require lower global warming potential (GWP) refrigerants, and push fleets toward zero-emission refrigeration technology.
The critical point: CARB's TRU rules apply based on where your unit operates, not where it's registered. A reefer fleet based in Ontario, Alberta, or Manitoba is subject to these requirements the moment it runs in California. There's no exemption for out-of-province or out-of-state registration.
This is about your reefer unit — not just your truck
CARB runs separate programs for truck engines and for TRUs. Even if your tractor is fully compliant with CARB's truck and bus regulations, your Carrier or Thermo King unit may have its own compliance obligations under the TRU ATCM. Both need to be in order before you pull into California.
What the TRU ATCM actually requires
The 2022 amendments to the TRU ATCM introduced a series of requirements that are now being phased in. Here's how the key obligations break down:
| Requirement | Effective Date | Status |
|---|---|---|
|
Low-GWP refrigerant New TRUs must use refrigerant with a GWP of 2,200 or lower (R-452A replaces R-404A). Both Carrier and Thermo King have transitioned their product lines accordingly. |
Dec 31, 2022 | Active |
|
TRU registration (ARBER) All TRU owners must register every unit operating in California with CARB's ARBER system, obtain a CARB ID number, and pay operating fees every three years. |
Dec 31, 2023 | Active |
|
CARB compliance labels TRU owners must affix CARB compliance labels to each unit every three years. Drivers must carry documentation and allow visual inspection if requested. |
Dec 31, 2023 | Active |
|
Facility reporting Refrigerated warehouses (20,000+ sq ft) and grocery DCs (15,000+ sq ft) must register with CARB and report quarterly on all TRUs operating at their facility. |
Dec 31, 2023 | Active |
|
Zero-emission TRU transition (straight trucks) CARB originally required a 15%-per-year phased transition of truck TRUs to ZE technology, reaching 100% ZE by end of 2029. The EPA declined to grant a waiver for this specific requirement in January 2025 — enforcement is currently paused. |
Was Dec 31, 2023 | Paused |
Don't confuse "paused" with "cancelled"
The zero-emission TRU transition requirement for straight trucks is paused pending the EPA waiver process — it has not been eliminated. CARB has made clear it intends to pursue ZE TRU requirements. Fleets that wait for absolute certainty before planning risk being caught flat-footed when enforcement resumes. All other TRU ATCM requirements — registration, labels, refrigerant, reporting — are active and enforced now.
What compliance looks like in practice
For carriers running Carrier Transicold or Thermo King units into California, getting compliant today involves four concrete steps:
1
Register every California-operating unit in ARBER
Each TRU needs a CARB identification number obtained through the ARBER system. You'll need the unit's model, model year, and serial number from the unit label, plus the engine manufacturer, model, and model year from the engine label. CARB provides label-finding guides specifically for Carrier Transicold (Kubota engines) and Thermo King (Isuzu and Yanmar engines).
2
Confirm your refrigerant
Units manufactured for sale in California from 2023 onward must use R-452A or another refrigerant with GWP ≤ 2,200. If your units are newer Carrier or Thermo King models, they're likely already compliant — but it's worth confirming the refrigerant type on the unit label before a California run. Older units running R-404A may need attention.
3
Affix CARB compliance labels and carry documentation
Each compliant TRU needs a current CARB compliance label affixed to the unit. Drivers operating in California must carry documentation and be prepared to allow a visual inspection if CARB enforcement personnel request it. Missing or outdated labels are one of the most common compliance gaps found during inspections.
4
Keep your unit in proper working order
A well-maintained unit is a compliant unit. CARB's TRU inspection process includes a visual check of the emissions control equipment — diesel oxidation catalysts, fuel filtration systems, and engine condition all factor in. Units with deferred maintenance are higher-risk on both compliance and inspection fronts.
From the AVRO team
The most preventable compliance issue we see is deferred maintenance on reefer units running California lanes. A failing diesel oxidation catalyst, worn fuel injectors, or a dirty fuel filtration system doesn't just hurt fuel efficiency — it creates an emissions control failure that can flag your unit during a CARB inspection. Keeping your Carrier or Thermo King in top condition is your first line of compliance defense. Browse our aftermarket parts to keep your units running clean.
Which units are affected?
The TRU ATCM covers a broad range of refrigeration equipment. Here's how coverage breaks down by unit type:
Straight truck TRUs
Class 5–7 straight trucks with diesel-powered reefer units. Most impacted by the zero-emission transition requirements — diesel-powered units can no longer be sold new for this application in California.
Trailer TRUs
Reefer units on refrigerated trailers — the most common configuration for long-haul temperature-controlled freight. Diesel units remain permissible for now; registration, labeling, and refrigerant requirements apply.
Domestic shipping containers & railcar TRUs
Diesel-powered TRUs on domestic shipping containers and railcars. Subject to lower PM emission standards and refrigerant requirements under the 2022 amendments.
The road ahead for reefer fleets
The direction CARB is moving is clear, even if the exact enforcement timelines continue to shift. Diesel-powered TRUs on straight trucks in California are effectively at end-of-life from a regulatory standpoint — new sales are prohibited, and a ZE transition requirement will eventually resume once the EPA waiver process resolves. Trailer TRUs have more runway, but the same trajectory applies.
For carriers with California exposure, the practical response is twofold: stay fully compliant on what's required today (registration, labeling, refrigerant, maintenance), and start planning the capital and infrastructure needed for the eventual transition to electric refrigeration — whether that's Carrier's eCool / Supra e-series or Thermo King's e1000 line.
The fleets that struggle won't be those caught off guard by new rules — they'll be the ones whose deferred maintenance created an avoidable compliance gap on a unit that was otherwise fine to operate.
16 states and counting
California's TRU requirements don't stop at the state line. Sixteen additional U.S. states have committed to adopting CARB's TRU regulations, with more expected to follow. If your lanes touch the U.S. Northeast, Pacific Northwest, or other early-adopter states, your TRU compliance picture extends well beyond California.
Keep your Carrier or Thermo King CARB-ready
Well-maintained units pass inspections. AVRO stocks high-quality aftermarket parts for Carrier Transicold and Thermo King — the same components that keep your reefer running clean and compliant, at a lower cost than OEM.
Shop AVRO Parts → More from the Knowledge Series