Compressors are used across a wide variety of products that RSL has to offer, most notably Air Conditioners, Heat Pumps and Refrigeration Systems. So, it is important for us to fully understand compressors and how to resolve issues with them when they occur.

With the system off and all leads disconnected to the compressor, you will need to measure resistance across each terminal and any copper tube connected to the compressor. In the case of a shorted compressor, there will be resistance between the two connections. A compressor that is not shorted will measure O.L (Open Limit).

To understand the potential reasons for a compressor being 'Short to Ground,' a thorough analysis of various possibilities is required. Frequently, this outcome is a result of short cycling, a factor that might be overlooked. Short cycling can be triggered by factors such as a low refrigerant charge, insufficient run time due to oversized equipment, or a defective temperature controller.

Another potential cause is a problem with the low pressure cut-out. In such cases, it's essential to inquire whether the Low Pressure Switch is consistently opening the compressor control circuit to deactivate the compressor with a reliable differential before it cycles on again.

A defective low pressure cut-out may present in several ways, including:

•  Over-heated compressor.
•  Seized due to loss of lubrication.
•  With electronic controlled evaporators: Low superheat alarms due to compressor off on high temperature cut-out protection.

If you find that you have come across a compressor that is ‘Short to Ground’, you should test the cut-in/cut-out settings of the Low Pressure Switch by monitoring and confirming these values through several cycles.

If you have any further questions about ‘Short to Ground’ compressors, or if you have any other questions regarding refrigeration, you can contact the Refrigeration Support Team for further advice. Alternatively, you can contact your local branch for support.