Whenever a shortage of refrigerant is suspected, this condition can be confirmed by identifying the source of leakage. A leak-test operation can be performed with a halide leak detector. The end of the exploring hose is passed around areas where a refrigerant leak is suspected. The air drawn into the hose passes through a copper reactor plate and through a small flame. If any refrigerant is contained in this air, the color of the flame turns slightly green. If a considerable quantity of refrigerant is leaking, the flame turns purple. When the location of leak has been determined, it is sometimes difficult to pinpoint the exact leak location. Soapsuds can be used to pinpoint the exact source of leak.