What 'low on gas' actually means
Air conditioning systems are sealed refrigerant circuits — the refrigerant inside doesn't get consumed and doesn't degrade in normal use. If a system is low on refrigerant, it's leaked out, period. Common leak points (in order of frequency) are: flare joint connections at the indoor and outdoor units (vibration loosens them over years), brazed joints on the high-side liquid line, Schrader valve cores at the outdoor unit, the outdoor unit's Schrader access ports themselves, and very occasionally a perforated evaporator coil or condenser coil. Most leaks are repairable on the day; coil leaks are usually a unit-replacement decision.
Why pressure testing matters before any recharge
F-Gas regulations require that any system being recharged with more than the equivalent of 10% of its nominal charge has its leak repaired before recharge — and that the repair is verified by pressure test. We pressure-test with dry nitrogen at 25–30 bar (well above operating pressure but below pipework rated pressure) and hold for at least 15 minutes, watching for pressure drop. A pressure-stable system passes; any drop tells us where to look for the leak using electronic detectors, ultrasonic listening or fluorescent UV dye.
Deep vacuum — the bit nobody talks about
After leak repair and before recharge, the system must be evacuated of all air and moisture using a two-stage vacuum pump pulled down to below 500 microns (0.5 millibar), measured with a digital micron gauge. This step is what separates a real recharge from a cowboy job. Air in a refrigerant system causes acid formation; moisture causes ice in the expansion valve and compressor damage. A 'quick' vacuum of 10 minutes is not enough — we typically pull down for 30–60 minutes and verify the gauge holds steady before introducing refrigerant.
Refrigerant types — R32, R410A, R407C, R22 and what you should know
Modern systems (post-2018) almost all use R32 — lower global warming potential, single-component, charged by weight. R410A is the previous generation and still widely used; also charged by weight. R407C is older and mostly seen on systems 15+ years old. R22 was the legacy refrigerant and has been banned for top-up since 2015; if you have an R22 system, any leak triggers a system replacement decision because you cannot legally add R22 to it. We carry calibrated gauges and adapters for all four and will tell you exactly what's in your system after a 30-second check.
What a proper F-Gas certificate looks like
Every Adapt re-gas finishes with a paper or PDF F-Gas record showing: date, engineer name and F-Gas certification number, system make/model/serial, refrigerant type, refrigerant added (weighed), refrigerant recovered (weighed), leak repair description, pressure-test result, vacuum reading, post-recharge running pressures and superheat. This is the document that keeps your manufacturer warranty live and that commercial operators need for F-Gas compliance audits.
When a re-gas isn't the right answer
If a system is over 12 years old, has had multiple previous recharges, is on R22, or has a leak in the coil itself, a re-gas is often throwing good money after bad. We'll always tell you straight — repair quote in one hand, replacement quote in the other, with no commission on the replacement decision. Sometimes the right answer is one more season on a re-gas while you budget for replacement; sometimes the right answer is to replace now.
