Toyota 4Runner: Problem Symptoms Table

Toyota 4Runner Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Manual Air Conditioning System) / Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Inspect the fuses and relays related to this system before inspecting the suspected areas below.

Front Air Conditioning Unit

Symptom	Suspected Area	See page
All functions of A/C system do not operate	Proceed to "IG Power Source Circuit"
	Proceed to "Back-up Power Source Circuit"
	Proceed to "Air Conditioning Control Panel Circuit"
	Replace air conditioning amplifier assembly
	LIN communication system
Air Flow Control: No blower operation	Proceed to "Blower Motor Circuit"
	Proceed to "Air Conditioning Control Panel Circuit"
	Replace air conditioning amplifier assembly
	LIN communication system
Air Flow Control: No blower control	Proceed to "Blower Motor Circuit"
	Proceed to "Air Conditioning Control Panel Circuit"
	Replace air conditioning amplifier assembly
	LIN communication system
Air Flow Control: Insufficient air flow	Proceed to "Blower Motor Circuit"
Air Flow Control: Insufficient air flow	Replace air conditioning amplifier assembly
Temperature Control: No cool air comes out	Check volume of refrigerant
	Check for refrigerant gas leak
	Replace cooler expansion valve
	Check cooler compressor assembly
	Check No. 1 pressure switch
	Proceed to "Air Conditioning Compressor Magnetic Clutch Circuit"
	Proceed to "Compressor Lock Sensor Circuit"
	Proceed to "Air Mix Damper Control Servo Motor Circuit"
	Proceed to "Ambient Temperature Sensor Circuit"
	Proceed to "Evaporator Temperature Sensor Circuit"
	Proceed to "Communication Malfunction (Bus Ic)"
	Proceed to "Air Conditioning Control Panel Circuit"
	Replace air conditioning amplifier assembly
	LIN communication system
Temperature Control: No warm air comes out	Proceed to "Air Conditioning Control Panel Circuit"
	Proceed to "Air Mix Damper Control Servo Motor Circuit"
	Proceed to "Communication Malfunction (Bus Ic)"
	Replace air conditioning amplifier assembly
	LIN communication system
Temperature Control: Output air is warmer or cooler than set temperature or response is slow	Check volume of refrigerant
	Check for refrigerant gas leak
	Replace cooler expansion valve
	Check cooler compressor assembly
	Replace heater radiator unit sub-assembly
	Check No. 1 pressure switch
	Proceed to "Air Conditioning Compressor Magnetic Clutch Circuit"
	Proceed to "Compressor Lock Sensor Circuit"
	Proceed to "Air Mix Damper Control Servo Motor Circuit"
	Proceed to "Air Inlet Damper Control Servo Motor Circuit"
	Proceed to "Ambient Temperature Sensor Circuit"
	Proceed to "Evaporator Temperature Sensor Circuit"
	Proceed to "Communication Malfunction (Bus Ic)"
	Proceed to "Air Conditioning Control Panel Circuit"
	Replace air conditioning amplifier assembly
	LIN communication system
No air inlet control	Proceed to "Communication Malfunction (Bus Ic)"
	Proceed to "Air Inlet Damper Control Servo Motor Circuit"
	Replace air conditioning amplifier assembly
No air flow mode control	Proceed to "Communication Malfunction (Bus Ic)"
	Proceed to "Air Outlet Damper Control Servo Motor Circuit"
	Replace air conditioning amplifier assembly
Engine coolant does not warm up quickly when the engine is cold (PTC heater does not operate)*	Proceed to "PTC Heater Circuit"
	Proceed to "Generator Signal Circuit"
	Check generator assembly
	Replace air conditioning amplifier assembly
Engine idle up does not occur or is continuous	Replace air conditioning amplifier assembly
	Replace ECM
	CAN communication system
Diagnostic trouble codes are not stored, and set mode is cleared when ignition switch is off	Proceed to "Back-up Power Source Circuit"
	Replace air conditioning amplifier assembly

*: w/ PTC Heater

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