Checking for Oil Stains
The presence of oil is one of the most significant red flags you can find during an inspection. Where there is oil, there is almost certainly a refrigerant leak—a major and often costly repair.
Refrigerant Leak Inspection
Refrigerant is mixed with oil to lubricate the compressor. When refrigerant leaks out of the system, it carries small amounts of this oil with it, leaving behind a tell-tale stain.
Where to Look for Oil
- Compressor Area Thoroughly inspect the compressor body and all copper piping connected to it. Pay close attention to joints and service valves.
- Condenser and Evaporator Coils Examine the surfaces and connections of both coils. Leaks often occur at the U-bends or where the copper pipes connect to the coil body.
What It Means
- A Guaranteed Problem Unlike cosmetic issues, an oil stain indicates a definite system fault. The unit is not operating as it should and will eventually fail to cool or heat.
- A Major Repair is Needed Fixing a refrigerant leak involves finding the leak, repairing it (often by brazing), and recharging the system with new refrigerant. This is a labor-intensive and expensive process.
Pro Tip: Stains Indicate History
Even old, dry-looking stains are a bad sign. They can indicate a slow leak that has been happening over time or a previous repair that may not have been successful. Any sign of oil warrants a deeper look by a professional.