Abstract: A method of cleaning an air conditioning system utilizes a maintenance unit. The maintenance unit has a recovery compressor, recovery condenser, a recovery evaporator, and recovery expansion valve. Operating the recovery compressor draws refrigerant from the air conditioning system, filters it, and passes it into a storage container. To clean, a control valve leading from the storage container is opened to flow refrigerant from the storage container into both the high pressure and low pressure sides of the air conditioning system compressor. The recovery compressor continues to operate to apply a pressure to the air conditioning system up to a maximum level. Once this is reached, or a selected time interval elapses, the pressure in the air conditioning system is again reduced and brought to a vacuum, causing refrigerant to flow back out of the air conditioning system, bringing with it foreign matter.

Abstract: A refrigerant recovery assembly will recover incompatible refrigerants. The assembly has two separate processing units. Each unit has a pair of hoses which connect to an air conditioning system for recovering refrigerant. Each unit has an expansion valve, an evaporator, a compressor, a condenser and one or more filters. The two units are mounted on a single frame and utilize common electrical controls. The electrical controls will not allow each unit to operate simultaneously. A single vacuum pump is used with each unit.

Abstract: A monitor used in refrigerant recovery systems to detect and reduce non-condensable vapor in a storage container. The monitor has a sampling reservoir that draws a sample of liquid refrigerant contained in a storage container. The sample of liquid refrigerant is allowed to reach equilibrium, providing a saturated vapor pressure, which is compared to the vapor pressure in an upper portion of the container. The difference in pressure between the sampling reservoir and the container indicating when the container should be exhausted.