Copyright Goodheart-Willcox Co., Inc. 816 Air-Conditioning Systems Use equipment-specific troubleshooting codes and troubleshooting charts prepared by the manufacturer to guide your testing. Using equipment-specific tools is gen- erally more effective than applying a generic troubleshoot- ing method. Wiring diagrams, motor information, system design conditions, and other information is often found on stickers affixed to the inside face of access panels. See Figure 32-29. Most air-conditioning system problems occur in the airflow or electrical subsystems. Thus, focus on these areas first. Ensure that the airflow subsystem is operating correctly before taking any measurements of the refriger- ant system. If the airflow over the condenser and evapo- rator is not sufficient, other system measurements will be affected. After the system airflow has been checked, focus on checks of the electrical system. Electrical testing is dis- cussed in general in Chapter 17, Electrical Troubleshooting Fundamentals and detailed troubleshooting of thermo- stats is found in Chapter 36, Thermostats. If a compressor motor, condenser fan motor, or indoor fan motor is not starting, check to see if the proper voltage is available at the device. If voltage is available, the problem is with the motor. If the proper voltage is not available at the device, troubleshoot the 24 V control circuit and the power circuit to find the fault. If the problem does not appear to be an electrical problem and the system is operating, measure the oper- ating conditions and compare the measurements to the manufacturer’s design specifications. See Figure 32-30. The following measurements will help identify potential problems: • Suction pressure • Discharge (head) pressure • Superheat • Subcooling • Compressor amperage draw • ΔT across evaporator The table in Figure 32-31 shows how some common refrigerant system problems impact these measurements. 32.6 Ductless Split Systems A ductless split system is a split air-conditioning sys- tem that does not use forced-air ductwork as a primary Central AC Testing Procedure Investigate Potential Causes Identified by Customer Interview or Initial Inspection ElectricalTesting of Outdoor Unit and Indoor Unit Follow Equipment-Specific Check Airflow Check System Measurements Directions Based on Trouble Codes or Troubleshooting Charts Goodheart-Willcox Publisher Figure 32-28. A basic general testing procedure for identifying a fault in a central air-conditioning system. This procedure presents the steps in one possible sequence, but a different sequence could be used based on technician preference, experience with the specific equipment, or other factors. CONTAINS HFC-401A FACTORY CHARGE DESIGN PRESSURE HI 448 PSIG LO 236 PSIG 5 LBS 2 OZS ELECTRICAL RATING NOMINAL VOLTS: 208/203 1 PH 60 HZ MIN 197 MAX 253 COMPRESSOR FAN MOTOR PH 1 RLA 12.8 LRA 64.0 PH 1 FLA 1.1 HP 1/5 17.1 MIN. CKT. AMPACITY AMPERAGE MINIMUM MAX FUSE OR CKT. BKR. FUSIBLE/COUPE CIRCUIT (HACR PER NEC) 25 1923F23499 74ACDX383 SERIAL NO: MODEL NO: Cool Air Corp. Goodheart-Willcox Publisher Figure 32-29. A condensing unit will have a label with information about the compressor motor, condensing fan motor, and system design pressures.