This is the third and final installment in the systematic air conditioning troubleshooting series. Part 1 dealt with low and high condenser entering air temperatures, an inefficient compressor, and noncondensables in the system. Part 2 dealt with liquid and suction line restrictions, overcharges and undercharges, and liquid subcooling in the condenser. Part 3 will cover how to diagnose air-side and refrigerant problems.