What is one method of leak testing a refrigeration unit?

Using liquid soap is a common and effective method for leak testing a refrigeration unit. When you apply a soap solution to potential leak points in the system, any escaping refrigerant will create bubbles in the soap. This visual indication allows technicians to easily identify the locations of leaks. This method is advantageous because it's straightforward, does not require specialized equipment, and can be performed quickly.

In contrast, the other methods listed may not be as practical or applicable for standard leak testing. Electric current typically pertains to electrical diagnostics rather than detecting refrigerant leaks. Thermal imaging, while useful for a variety of inspections, often requires more advanced technology and can be less effective at pinpointing small gas leaks compared to the simplicity of using soap. Pressure release involves lowering the pressure in the system, which can be useful in some contexts but is not a direct method of identifying leaks like the application of liquid soap.