Copyright Goodheart-Willcox Co., Inc. 818 Air-Conditioning Systems • Mini-split systems. Mini-split systems consist of one indoor unit and one outdoor unit. A mini-split is a single- zone system because the system has a single indoor unit. • Multi-split systems. Multi-split systems consist of a single outdoor unit connected to several indoor units. In a single-zone multi-split system, each indoor unit has a line set connected to the outdoor unit. An outdoor unit may be able to support two to eight indoor units. In some cases, the indoor units are controlled by a single thermostat. In other cases, each indoor unit has its own thermostat. • VRF systems. VRF (variable refrigerant flow) systems are multi-split, multizone systems. A single outdoor unit is connected to many indoor units, with each unit having its own thermostat setting. Instead of the individual line sets used in mini-split systems, VRF systems use a trunk and branch piping system to connect the outdoor unit to the indoor units. Outdoor units Indoor units Mitsubishi Electric, HVAC Advanced Products Division Figure 32-32. This multizone ductless split system consists of four outdoor units and six indoor units. Refrigerant line sets connect the outdoor units to the indoor units. 32C: Residential Central Air-Conditioning: Poor Cooling Overview Continuing from Service Call Troubleshooting 32A and 32B, Sharon’s customer interview with Mr. Gonzalez revealed no significant information other than confirming that the system has not had any previous problems. Her initial inspection also did not identify any potential problems. All system components are operating, but the system is not able to keep up with the moderate cooling load. System Testing Sharon begins testing the system with the goal of identifying the problem. Analyze and Discuss 1. What are some items that could aid Sharon in her system troubleshooting? 2. What would be a good overall approach for Sharon to apply to find the cause of the problem? 3. What would be a poor approach for Sharon to apply? 4. What is the difference between a good troubleshooting approach and a bad troubleshooting approach? Service Call Troubleshooting