How to Tell If You Have a Refrigerant Leak

Wondering if your air conditioner or heat pump has a refrigerant leak? Catching the problem early protects comfort, energy bills, indoor air quality, and the life of your compressor. Below are practical signs, safe checks, and how professionals confirm and repair a leak in compliance with regulations and insurance requirements.

What a refrigerant leak means

Refrigerant carries heat. When it escapes, your system loses capacity, runs longer, and can ice up. A leak is not a normal condition, and simply adding more refrigerant does not fix the root cause. In many jurisdictions, knowingly operating or recharging a leaking system is not allowed, and only EPA Section 608 certified technicians may handle refrigerants.

Common signs of a refrigerant leak

• AC not cooling like it used to, or run times get much longer on hot afternoons.
• Weak airflow feels lukewarm at the supply vents even with a low thermostat setting.
• Frozen evaporator coil or ice on the refrigerant line near the air handler or outdoor unit.
• Water under the air handler after ice melts and the indoor coil thaws.
• Hissing noise or occasional bubbling noise around the line set, service valves, or evaporator.
• Oil residue on service port caps, flare fittings, or brazed joints (oil can travel with refrigerant).
• Rising energy bills without a change in weather or usage.
• Thermostat never reaches setpoint; some rooms become hot spots.
• On ductless mini-split systems, error codes and intermittent defrost or low-capacity behavior.

Safe checks you can do

• Inspect your air filter and replace if dirty to rule out airflow restrictions.
• Look (don’t touch) for frost or a frozen evaporator coil; shut the system off if you see ice.
• Listen for a faint hissing noise near the indoor unit, outdoor condenser, or line set.
• Compare return and supply air: a very small temperature drop under load can point to low charge. This is not a diagnosis by itself, but it is a clue.

Important: Avoid opening service ports or handling refrigerant lines. Refrigerant can cause frostbite, and improper actions can damage the compressor or void warranties.

How professionals confirm a refrigerant leak

• Electronic leak detector (sniffer) to trace tiny leaks around coils, flare fittings, and service valves.
• UV dye test in select systems where the manufacturer allows, followed by inspection with a UV lamp.
• Nitrogen pressure test and decay monitoring, often combined with a trace refrigerant, to pinpoint hard-to-find leaks.
• Weigh-out and charge-by-weight procedures to verify the correct refrigerant amount per nameplate.

Licensed pros follow EPA Section 608 rules for recovery, evacuation, and charging, and they document findings for warranty and insurance purposes.

Is it safe to keep running with low refrigerant?

Generally, no. Low refrigerant can cause the evaporator to freeze, starve lubrication, overheat the compressor, and flicker between freeze and floodback. That risks compressor damage, high humidity indoors, and poor air quality. Some refrigerants are odorless and can displace oxygen in confined spaces. If you suspect a leak, power the system off and seek qualified diagnostics.

Repair the leak, don’t just refill

A lasting fix means finding and repairing the leak source: a rubbed line, a weak flare on a mini-split, formicary corrosion in a copper coil, or a leaky service valve core. After repair, the circuit is evacuated to deep vacuum and charged precisely. Topping off without repair is a temporary patch at best and may violate rules against venting refrigerant.

What causes leaks

• Vibration or rub-outs where copper contacts metal edges or each other.
• Formicary corrosion in indoor coils, especially in certain environments.
• UV and heat damage to insulation or line set coverings outdoors.
• Improper torque on flare fittings in ductless mini-split and VRF style systems.
• Service valve or Schrader core seepage at the service port.
• After a compressor burnout, acid formation can attack internal components if not properly cleaned.

Prevention tips

• Annual maintenance: clean coils, verify airflow, inspect insulation, and check electrical connections.
• Protect and support line sets; avoid sharp bends and rub points.
• Use manufacturer-approved torque and sealing practices on flares and valves.
• Ensure correct refrigerant charge and superheat/subcool targets after service.

Insurance, code, and documentation

Many building codes and warranties require licensed work on refrigerant systems, and homeowners or commercial insurance carriers often ask for detailed, licensed repair records. Proper leak detection reports, repair documentation, and charge logs help with insurance documentation and future warranty claims.

Service area and who we are

#1 AC Guys is a family HVAC company based in Southern California. Our 4th generation engineers bring 80+ years of engineering know-how to residential and commercial systems, especially large and complex projects. Our mission is simple: healthy air in the home for a healthy life.

Our engineers received factory training at Fujitsu (Japan), Mitsubishi Elektrik (Thailand), Midea (China), Gree (China), and Hier (China). We serve Los Angeles County and nearby regions including Orange County, Ventura County, and Western Riverside County, with projects in cities such as Pasadena, Glendale, Burbank, Santa Monica, Long Beach, Anaheim, Irvine, Santa Ana, Thousand Oaks, Oxnard, Camarillo, Riverside, Corona, and Temecula.

Quick FAQ

• Are refrigerants colored or scented? Most modern refrigerants are colorless and odorless, so rely on the signs above and professional testing.
• Do heat pump leak symptoms differ? No—signs like ice on the refrigerant line, hissing noise, and poor capacity apply to cooling and heating modes.
• Can I add refrigerant myself? Handling refrigerant requires EPA Section 608 certification and specialized tools; incorrect charging can cause compressor damage.