Air Conditioner Controller (ACF) Diagnostic Trouble Codes E21 Freeze Control Switch Open Circuit Freeze control switch open circuit. AH91621,000016E –19–15MAR06–1/1 Harness Diagnostics –1/1 TM2361 (24JUN08) 9001-40-7 450DLC Excavator Operation and Tests 062608 PN=195 3 Continuity Check Disconnect harness from solar sensor and air conditioner and heater controller. Check continuity between appropriate pins on air conditioner and heater controller connector and solar sensor. Is there continuity between air conditioner controller and solar sensor? YES: Air conditioner controller malfunction. NO: Open circuit in harness. Repair or replace harness.
See Cab Harness (W1) Wiring Diagram, see Monitor Harness (W3) Wiring Diagram, and See Air Conditioner Harness (W6) Wiring Diagram. (Group 9015-10.) – – –1/1 9001 40 7 1 Connector Check Check harness connection to freeze control 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