Copyright Goodheart-Willcox Co., Inc. Chapter 32 Residential Split Air-Conditioning Systems 819 10 Most ductless systems are available as cooling-only systems and as heat pump systems. The heat pump systems can reverse the refrigerant flow so the outdoor coil serves as the evaporator and the indoor coil serves as the con- denser. VRF systems are available as heat pump systems and heat recovery systems. VRF systems are discussed in Chapter 33, Commercial Air-Conditioning Systems. 32D: Residential Central Air-Conditioning: No Cooling Overview The owner of a 2300 ft2 residence, Mr. Andrews, has reported that his split central air-conditioning system is not providing cooling. Upon arriving at the residence, the technician, Tim, identifies himself and verifies that Mr. Andrews requested service. Before entering the residence, Tim puts on shoe covers. Customer Interview Mr. Andrews explains that the air-conditioning system is not blowing cold air, so he turned the thermostat to Off. Tim asks questions to learn that Mr. Andrews noticed the problem the previous day and that the system had been operating fine two days ago. Tim also learns that the system was serviced earlier in the year and that no repair work has been needed for the system. Initial Inspection Tim begins by inspecting the thermostat. The digital display is working. Tim inspects the indoor unit and finds that the air filter appears to have been changed recently. He inspects the interior of the air handler and sees nothing that indicates a problem. The ductwork looks fine and there are no signs of leaks on the refrigerant tubing. Tim inspects the outdoor unit and does not see any problems. The simplified ladder diagram for the system is shown here. System Testing Tim sets the thermostat to call for cooling. He hears the thermostat click and hears the indoor blower start. He goes to the outdoor unit and observes that the compressor starts, runs briefly, and then stops. The condenser fan does not start. Analyze and Discuss 1. Based on the information provided, what are some possible causes of the problem? 2. What could be some useful tests for Tim to perform to identify the problem? 3. Select one of the possible causes you identified in Question 1 and describe the procedure for repairing the issue. 4. After completing the repair described in Question 2, how would Tim check to ensure that the repair was done correctly? How would Tim check the system to ensure that the repair solved the original problem? Service Call Troubleshooting