Symptoms
- Cooling gets gradually weaker over weeks or months
- Ice forming on the indoor coil or outdoor lines
- Hissing or bubbling sound near the indoor or outdoor unit
- Higher electric bills for similar usage
Likely causes
- CommonSmall leak at a fitting or joint in the refrigerant linesVibration and age can loosen fittings enough to leak slowly over time.
- CommonCorrosion (formicary corrosion) in the coilTiny pinhole leaks can develop in the coil itself from a slow chemical corrosion process over years.
- PossiblePhysical damage to the lines from a lawnmower, tools, or wildlifeExposed refrigerant lines outside can be nicked or punctured.
- Less commonManufacturing defect or weld failureOccasionally a factory joint fails prematurely.
What to do
- Note whether cooling performance has been gradually declining rather than failing suddenly.
- Check the indoor coil and outdoor lines for visible ice, which often accompanies a refrigerant leak.
- Listen near the indoor and outdoor units for a hissing or bubbling sound that could indicate an active leak.
- Check for oily residue around refrigerant line fittings, since refrigerant oil often leaves a visible trace at a leak point.
- Don't attempt to add refrigerant yourself; it requires EPA certification and proper equipment.
- Call a technician for leak detection and repair, since simply adding refrigerant without fixing the leak is a temporary and wasteful fix.
When to call a pro
Call a licensed HVAC technician for leak detection and repair; refrigerant work legally requires EPA certification.
Safety
Use caution
Refrigerant is a controlled substance and handling it requires EPA certification; never attempt to add or recover it yourself.