A/C System Symptom Diagnosis

SYMPTOM DIAGNOSIS DESCRIPTION CHART

Condition	Possible Cause	Action
No cool air comes out (A/C compressor does not operate)	No refrigerant	Perform recovery, evacuation and charge referring to OPERATION PROCEDURE FOR REFRIGERANT CHARGE: MANUAL A/C .
	Fuse blown	Check related fuses, and then check for short circuit to ground .
	A/C switch faulty	Check A/C switch referring to A/C SWITCH, AIR FLOW SELECTOR (DEFROSTER SWITCH) AND AIR INTAKE SELECTOR INSPECTION: MANUAL A/C .
	Blower speed selector faulty	Check blower speed selector referring to BLOWER SPEED SELECTOR INSPECTION .
	Evaporator temperature sensor faulty	Check evaporator temperature sensor referring to EVAPORATOR TEMPERATURE SENSOR INSPECTION: MANUAL A/C .
	A/C refrigerant pressure sensor faulty	Check A/C refrigerant pressure sensor referring to A/C REFRIGERANT PRESSURE SENSOR AND ITS CIRCUIT INSPECTION: MANUAL A/C .
	Wiring or grounding faulty	Repair as necessary .
	ECM faulty	Check ECM referring to A/C SYSTEM INSPECTION AT ECM: MANUAL A/C .
	Magnet clutch faulty	Check magnet clutch referring to MAGNET CLUTCH INSPECTION: MANUAL A/C .
	Compressor drive belt loosened or broken	Adjust or replace drive belt .
	Compressor faulty	Check compressor .
	Compressor relay faulty	Check compressor relay referring to A/C SYSTEM RELAY INSPECTION: MANUAL A/C .
	BCM faulty	Check BCM referring to INSPECTION OF BCM AND ITS CIRCUITS .
No cool air comes out (radiator cooling fan motor does not operate)	Fuse blown	Check related fuses, and then check for short circuit to ground .
	Wiring or grounding faulty	Repair as necessary .
	Condenser cooling fan relay faulty	Check condenser cooling fan motor relay referring to A/C SYSTEM RELAY INSPECTION: MANUAL A/C .
	Condenser cooling fan motor faulty	Check condenser cooling fan motor referring to CONDENSER COOLING FAN INSPECTION: MANUAL A/C .
	ECM faulty	Check ECM referring to A/C SYSTEM INSPECTION AT ECM: MANUAL A/C .
	Fuse blown	Check related fuses, and then check for short circuit to ground .
No cool air comes out (blower motor does not operate)	Blower motor relay faulty	Check blower motor relay referring to BLOWER MOTOR RELAY INSPECTION .
	Blower motor resistor faulty	Check blower motor resistor referring to BLOWER MOTOR RESISTOR INSPECTION .
	Blower speed selector faulty	Check blower speed selector referring to BLOWER SPEED SELECTOR INSPECTION .
	Wiring or grounding faulty	Repair as necessary .
	Blower motor faulty	Check blower motor referring to BLOWER MOTOR INSPECTION .
Cool air does not come out or insufficient cooling (A/C compressor normal operation)	Insufficient or excessive charge of refrigerant	Check the amount of refrigerant and system for leaks .
	Condenser clogged	Check condenser referring to CONDENSER ASSEMBLY ON-VEHICLE INSPECTION: MANUAL A/C .
	A/C evaporator clogged or frosted	Check A/C evaporator and evaporator temperature sensor referring to EVAPORATOR INSPECTION: MANUAL A/C and EVAPORATOR TEMPERATURE SENSOR INSPECTION: MANUAL A/C .
	Evaporator temperature sensor faulty	Check evaporator temperature sensor referring to EVAPORATOR TEMPERATURE SENSOR INSPECTION: MANUAL A/C .
	Expansion valve faulty	Check expansion valve referring to EXPANSION VALVE INSPECTION: MANUAL A/C .
	Desiccant clogged	Check desiccant and cap with filter .
	Compressor drive belt loosened or broken	Adjust or replace drive belt .
	Magnet clutch faulty	Check magnet clutch referring to MAGNET CLUTCH INSPECTION: MANUAL A/C .
	Compressor faulty	Check compressor .
	Air in A/C system	Replace condenser, and then perform evacuation and charge referring to OPERATION PROCEDURE FOR REFRIGERANT CHARGE: MANUAL A/C .
	Air leaking from HVAC unit or air duct	Repair as necessary .
	Heater and ventilation system faulty	Check HVAC unit .
	Blower motor faulty	Check blower motor referring to BLOWER MOTOR INSPECTION .
	Excessive compressor oil in A/C system	Drain excessive compressor oil from A/C system circuit and compressor .
Cool air does not come out only intermittently	Wiring connection faulty	Repair as necessary .
	Evaporator temperature sensor faulty	Check evaporator temperature sensor referring to EVAPORATOR TEMPERATURE SENSOR INSPECTION: MANUAL A/C .
	Expansion valve faulty	Check expansion valve referring to EXPANSION VALVE INSPECTION: MANUAL A/C .
	Excessive moisture in A/C system	Replace condenser, and then perform evacuation and charge referring to OPERATION PROCEDURE FOR REFRIGERANT CHARGE: MANUAL A/C .
	Magnet clutch faulty	Check magnet clutch referring to MAGNET CLUTCH INSPECTION: MANUAL A/C .
	Excessive amount of refrigerant	Check the amount of refrigerant .
Cool air comes out only at high speed	Condenser clogged	Check condenser referring to CONDENSER ASSEMBLY ON-VEHICLE INSPECTION: MANUAL A/C .
	Insufficient charge of refrigerant	Check the amount of refrigerant and system for leaks .
	Air in A/C system	Replace condenser, and then perform evacuation and charge referring to OPERATION PROCEDURE FOR REFRIGERANT CHARGE: MANUAL A/C .
	Compressor drive belt loosened or broken	Adjust or replace drive belt .
	Compressor faulty	Check compressor .
Cool air does not come out only at high speed	Excessive amount of refrigerant	Check the amount of refrigerant .
Cool air does not come out only at high speed	A/C evaporator frosted	Check A/C evaporator and evaporator temperature sensor referring to EVAPORATOR INSPECTION: MANUAL A/C and EVAPORATOR TEMPERATURE SENSOR INSPECTION: MANUAL A/C .
Insufficient air flow of cooled air	A/C evaporator clogged or frosted	Check A/C evaporator and evaporator temperature sensor referring to EVAPORATOR INSPECTION: MANUAL A/C and EVAPORATOR TEMPERATURE SENSOR INSPECTION: MANUAL A/C .
	Air leaking from HVAC unit or air duct	Repair as necessary .
	Blower motor faulty	Check blower motor referring to BLOWER MOTOR INSPECTION .
	Wiring or grounding faulty	Repair as necessary .