True or False: Adding liquid refrigerant directly into the liquid receiver should be done with the compressor running.

Adding liquid refrigerant directly into the liquid receiver should be done with the compressor off to ensure safety and system integrity. When refrigerant is added with the compressor running, there is a risk of flooding the compressor, which can lead to liquid refrigerant entering the compressor’s cylinders. This can cause damage, as compressors are designed to compress gases, not liquids.

By having the compressor off, the system can safely handle the additional refrigerant without the risk of liquid returning to the compressor. It's critical to maintain the proper operation and longevity of the equipment, taking precautions to avoid issues such as liquid slugging, which occurs when liquid refrigerant enters the compressor. Therefore, the correct approach is to perform this task with the compressor not operating.