The basic working process Inverter Multi units are: central air show when the fault does not boot, the outdoor refrigeration unit from the indoor unit to absorb the refrigerant vapor is compressed, condensed to each indoor unit transfer of liquid refrigerant. Tianjin central heating air conditioning failure when low pressure alarm, outdoor refrigeration unit absorbed from the condenser refrigerant vapor after compression to each indoor unit refrigerant vapor transport. Each indoor unit is arranged through concealed in the ceiling. Through its return air to the air intake, into the post-heat exchange, then take place back to the way back to the indoor air from the air outlet will be processed later. Due to the use of air conditioning and refrigeration function for long periods of central air-conditioning failure, outside of stale air through the duct will accumulate on the air filter or evaporator, with the accumulation of dust will be blocked portion of the intake passage central air conditioning fault finding, resorted the outlet air volume reduction, resulting in cool enough, affect the cooling effect. Further, since the spring is the high incidence of respiratory diseases and skin diseases, prone to bacteria and mites air conditioning inside, experts recommend that air conditioning should be cleaned at least a year or more times.