There are many things that can cause a motor burn out in a compressor. The best way to clean up after a burn out is to prevent the burn out from happening in the first place. Things such as moisture, non-condensable and overheating are preventable causes of motor burn out. Proper evacuation and charging coupled with proper system maintenance (replacing the filter, cleaning condensers, and properly adjusted controls) will prevent many burnouts from occurring. Power issues also cause many compressor burnouts. Phase monitors for three phase and voltage monitors for single phase compressors can help prevent these types of burnouts.
When burnouts do occur what is the best way to clean up our system? Determine the severity of the burnout buys using an acid test kit. A negative acid test result indicates a mild burn out while a positive result indicates a severe burnout.
A mild burn out can normally be cleaned up with the use of an over-sized drier, triple evacuation, and proper recharging. Proper evacuation cannot be performed without the use of a good vacuum pump and a micron gauge.
A severe burn out will take much more involved methods of clean up. After replacing the compressor an oversized HH core filter drier and an HH core suction filter should be installed. After proper evacuation (triple evacuation) and recharging the system should be placed back in operation. The pressure drop should be monitored across the suction filter, and the filter should be replaced when the pressure drop exceeds manufacture recommendations. More than one filter change may be required on a system with extreme burnouts. A second acid test may be needed to confirm the system is clean. The suction filter should be removed after clean up as a plugged suction filter can also cause compressor failure. When changeable core suction filters are being used the core can be removed or replaced with a filter element.
A system flush like RX11 is available that can also be used for clean up after burnouts. RX11 is a refrigerant-based flush that if used properly will flush the acid contaminated oil from the system, piping, and valves. Install a new filter drier, the compressor, evacuate properly (triple evacuation) and re-charge the system normally. A proper evacuation will ensure any residual flush has been removed from the system. This method will be much faster than the suction filter method. RX11 is approved for use by many A/C OEMs such as Bryant and Daikin.