This Preliminary Information communication provides information to the technician about vehicles that have poor air conditioning performance above 80 Degrees Fahrenheit. Technician will need to ensure that the system charge is correct. Technician should be advised that engineering has determined that there may be two issues that could cause the concern. First the technician will need to monitor the High and low pressure with manual gauges and Global Diagnostic System 2 monitoring the AC Compressor Solenoid Commanded % in the ECM /HVAC data. If the pressures start to equalize but the Commanded Compressor % returns to 100%, turn off the Air Conditioning using the switch and then turn it back on or shut off the engine and restart it. If system begins to blow cold again and the gauges recover to normal, replace the Air Conditioning compressor. Second the technician should monitor and record the Heater-Vent-Air Conditioning readings. If it is found most of these readings are in specification but the low side pressure is at the low end of that specification and the Evaporator Air Temperature Sensor reads approximately 10 degrees or more higher than the technician should infrared thermometer measure the temperature of the 2 locations, about 2 inches in from the edge of the core of the condenser. f there a difference of more than 10 degrees Fahrenheit top to bottom, replace the condenser.
