AC Refrigerant Leak: Signs, Causes & What to Do

Refrigerant is the lifeblood of your air conditioning system — it's the substance that actually absorbs heat from your home and rejects it outside. When it leaks, your AC loses its ability to cool effectively, your energy bills spike, and the compressor is put at risk of permanent damage. Here's what you need to know.

How Does Refrigerant Work?

Unlike fuel, refrigerant is not consumed — it circulates in a sealed loop indefinitely. If your system is low on refrigerant, it means there is a leak somewhere in the system. Simply "topping it off" without finding and repairing the leak is a temporary band-aid that will only need to be repeated — and it's illegal under EPA regulations to knowingly vent refrigerant into the atmosphere.

Warning Signs of a Refrigerant Leak

• Warm air from vents despite the system running continuously
• Ice on the refrigerant lines or evaporator coil — counterintuitive, but low refrigerant causes the coil to drop below freezing
• Hissing or bubbling sounds from the indoor unit or refrigerant lines
• Higher than normal electric bills — the system runs longer to achieve the same cooling
• Oily residue near refrigerant line connections (refrigerant oil leaks with the refrigerant gas)
• Humidity problems indoors — a properly charged system dehumidifies effectively; an undercharged one does not

Common Causes of Refrigerant Leaks

• Formicary corrosion — a chemical reaction between copper refrigerant lines, formic acid (from household products like adhesives and cleaning supplies), oxygen, and moisture. Creates tiny pinholes in the evaporator coil. Extremely common in Miami homes.
• Vibration wear — over time, vibration from the compressor can wear through refrigerant line connections or fittings
• Factory defects — less common but occurs, especially in lower-quality equipment
• Physical damage — lawn equipment, pest activity, or improper handling during service
• Schrader valve failure — the valve used to check and add refrigerant can leak over time

What We Do to Fix a Refrigerant Leak

1. Electronic leak detection — we use a sensitive electronic detector to pinpoint the exact location of the leak
2. Assess repair vs. replace — small leaks in accessible locations can be repaired; leaks in the evaporator coil often require coil replacement or full system replacement depending on age
3. Pressure test — after repair, we pressure-test the system to confirm no remaining leaks
4. Evacuate the system — we pull the system into a deep vacuum to remove moisture and air
5. Recharge to specification — we add the precise manufacturer-specified charge using calibrated equipment
6. Verify performance — we measure supply/return temperature differential and operating pressures to confirm proper operation

The Cost of a Refrigerant Repair

Costs vary significantly by location and extent:

• Minor leak repair at an accessible fitting: $150–$400
• Evaporator coil replacement: $800–$2,000
• Refrigerant recharge (R-410A, after repair): $150–$400 depending on pounds needed

For older systems using R-22, a coil leak often makes system replacement the more economical choice given the extreme cost of R-22 refrigerant today.