Air Conditioner Controller (ACF) Diagnostic Trouble Codes E51 Abnormal High/Low Pressure Switch Abnormal high/low pressure switch. AH91621,0000173 –19–15MAR06–1/1 Harness Diagnostics –1/1 TM2361 (24JUN08) 9001-40-11 450DLC Excavator Operation and Tests 062608 PN=199 2 Open Circuit Check Disconnect harness from servomotor and air conditioner and heater controller. Check continuity between pins on controller and servomotor connector. Is there continuity on the appropriate pins? IMPORTANT: Some wires between air conditioner controller and air conditioner servomotor are spliced with other control, power, and ground circuits. Use caution when checking and testing wires. YES:
Air conditioner and heater mixer servomotor malfunction. NO: Repair or replace harness. See Air Conditioner Harness (W6) Wiring Diagram. (Group 9015-10.) – – –1/1 9001 40 11 1 Connector Check Check harness connection to high/low pressure switch and air conditioner and heater controller. Are connectors clean and free from debris? Are pins straight and do they make a good connection? YES: Go to Open Circuit Check. NO: Repair or replace connector or pins. – – –1/1 2 Open Circuit Check Disconnect harness from high/low pressure switch and air conditioner and heater controller. Check continuity between pins on controller and high/low pressure switch connector.
Is there continuity on the appropriate pins? YES: High/low pressure switch malfunction. NO: Repair or replace harness. See Air Conditioner Harness (W6) Wiring Diagram. (Group 9015-10.) – – –1/1