The sentence that matters
A refrigeration system is a closed loop. The refrigerant circulates and is never consumed. So when someone tells you a system is low on refrigerant, they have told you there is a leak, whether or not they used that word.
For years the industry handled this by topping systems up annually and moving on. That era has ended for most walk-in equipment, and the change took effect at the start of this year.
What changed in January 2026
Under the AIM Act, the leak repair requirements for commercial refrigeration now apply to appliances with a full charge of 15 pounds or more, down from the previous 50-pound threshold. That single change pulls a large share of walk-in condensing units into scope for the first time.
In practice it means:
- Leaks above the applicable leak rate have to be repaired, not topped up, within set timeframes.
- Repairs have to be verified after the work.
- Records have to be kept — full charge, refrigerant added, dates, leak rate calculations, inspections.
- Systems with a history of leaks need periodic leak inspections.
The operator carries this obligation, not the contractor. Which means the quality of the paperwork your technician leaves behind is now part of what you are buying.
How to tell you have one
- Gradual capacity loss over weeks or months. The box creeps up a degree at a time. This is the classic slow-leak signature.
- Ice on the inlet end of the evaporator only, with the outlet end dry. A starved coil.
- Short cycling on the low-pressure switch.
- Oil staining at a joint, a valve, a flare or along the coil. Refrigerant carries oil, so where refrigerant escapes, oil marks the spot. This is the single most useful visual clue there is.
- Hissing or bubbling at the coil or line set.
- A history of having been topped up before. If anyone has added refrigerant to this system in the past, the leak was there then too.
Where they actually leak
In our experience on walk-ins, in rough order: flare and brazed joints that have fatigued from vibration; Schrader valve cores, which are a trivial part and a very common leak; evaporator coils corroded from the inside of a wet, salty, acidic kitchen environment; condenser coils corroded from outside, which in harbour-adjacent Boston is accelerated dramatically; and line sets where they pass through a wall or rub against a support.
The A2L transition
Newer walk-in equipment is shipping with A2L refrigerants, which are mildly flammable and have handling, leak detection and ventilation requirements that the older HFCs did not. If you are buying new equipment or replacing a condensing unit, this affects what is involved in servicing it and who is qualified to do so. It is worth asking about before you buy rather than after.
How we handle a leak call
Electronic leak detection across the whole circuit, with ultraviolet dye and nitrogen pressure testing where the leak is not immediately apparent. The leak gets repaired and the repair gets verified. Then evacuation to a proper vacuum and recharge by weight, not by guesswork at the gauge.
And you get the paperwork: system charge, refrigerant added, leak rate, what was found and where, and what was done about it. That record is yours, it builds a history for each system, and if an inspector ever asks, you have it. We would rather hand you that than a cheaper invoice for gas you will have to buy again next year.
Questions we get asked
How do I know if my system is in scope for the leak rules?
The threshold is based on the full charge of the appliance, not its size in cubic feet. Systems holding 15 pounds or more of refrigerant are in scope as of January 2026. A good many walk-in condensing units sit above that, including ones that were comfortably outside the old 50-pound threshold.
What records am I supposed to keep?
Charge size for each system, dates and amounts of any refrigerant added, leak rate calculations, and records of leak inspections and repairs. We leave this information on the written report after every visit so it accumulates in your file rather than ours.
Why did my repair cost more than just adding gas?
Because finding a leak takes time and fixing it is real work, whereas adding gas takes twenty minutes. Adding gas also means buying the same refrigerant again next year, at prices that are climbing as the phase-down tightens, and it is no longer permitted on systems in scope.