The System Diagnostics and Troubleshooting Procedures provides the reader with the necessary information to successfully diagnose air conditioning and refrigeration system problems. Systematic troubleshooting and diagnostics airflow problems, refrigerant cycle malfunctions, suction and liquid line restrictions, oil logged evaporator, undercharge, overcharge, compressor inefficiencies, dirty condenser, air in the system, restricted metering device. Low and high condenser entering air temperatures are detailed.