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.
Symptom | Suspected Area | See page |
|---|---|---|
All functions of A/C system do not operate |
Proceed to "IG Power Source Circuit" |
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Proceed to "Back-up Power Source Circuit" |
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Proceed to "Air Conditioning Control Panel Circuit" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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Air Flow Control: No blower operation |
Proceed to "Blower Motor Circuit" |
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Proceed to "Air Conditioning Control Panel Circuit" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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Air Flow Control: No blower control |
Proceed to "Blower Motor Circuit" |
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Proceed to "Air Conditioning Control Panel Circuit" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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Air Flow Control: Insufficient air flow |
Proceed to "Blower Motor Circuit" |
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Replace air conditioning amplifier assembly |
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Temperature Control: No cool air comes out |
Check volume of refrigerant |
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Check for refrigerant gas leak |
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Replace cooler expansion valve |
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Check cooler compressor assembly |
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Check No. 1 pressure switch |
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Proceed to "Air Conditioning Compressor Magnetic Clutch Circuit" |
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Proceed to "Compressor Lock Sensor Circuit" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Driver Side)" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Passenger Side)" |
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Proceed to "Room Temperature Sensor Circuit" |
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Proceed to "Ambient Temperature Sensor Circuit" |
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Proceed to "Evaporator Temperature Sensor Circuit" |
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Proceed to "Driver Side Solar Sensor Short Circuit" |
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Proceed to "Front Passenger Side Solar Sensor Short Circuit" |
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Proceed to "BUS IC Communication Malfunction" |
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Proceed to "Air Conditioning Control Panel Circuit" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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Temperature Control: No warm air comes out |
Proceed to "Air Conditioning Control Panel Circuit" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Driver Side)" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Passenger Side)" |
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Proceed to "Room Temperature Sensor Circuit" |
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Proceed to "Ambient Temperature Sensor Circuit" |
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Proceed to "Driver Side Solar Sensor Short Circuit" |
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Proceed to "Front Passenger Side Solar Sensor Short Circuit" |
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Proceed to "BUS IC Communication Malfunction" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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Temperature Control: Output air is warmer or cooler than set temperature or response is slow |
Check volume of refrigerant |
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Check for refrigerant gas leak |
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Replace cooler expansion valve |
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Check cooler compressor assembly |
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Replace heater radiator unit sub-assembly |
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Check No. 1 pressure switch |
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Proceed to "Air Conditioning Compressor Magnetic Clutch Circuit" |
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Proceed to "Compressor Lock Sensor Circuit" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Driver Side)" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Passenger Side)" |
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Proceed to "Air Inlet Damper Control Servo Motor Circuit" |
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Proceed to "Room Temperature Sensor Circuit" |
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Proceed to "Ambient Temperature Sensor Circuit" |
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Proceed to "Evaporator Temperature Sensor Circuit" |
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Proceed to "Driver Side Solar Sensor Short Circuit" |
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Proceed to "Front Passenger Side Solar Sensor Short Circuit" |
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Proceed to "BUS IC Communication Malfunction" |
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Proceed to "Air Conditioning Control Panel Circuit" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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Temperature Control: No temperature control (only MAX COOL or MAX WARM) |
Proceed to "Air Conditioning Control Panel Circuit" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Driver Side)" |
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Proceed to "Air Mix Damper Control Servo Motor Circuit (Passenger Side)" |
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Proceed to "Room Temperature Sensor Circuit" |
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Proceed to "Ambient Temperature Sensor Circuit" |
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Proceed to "Evaporator Temperature Sensor Circuit" |
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Proceed to "Driver Side Solar Sensor Short Circuit" |
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Proceed to "Front Passenger Side Solar Sensor Short Circuit" |
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Proceed to "BUS IC Communication Malfunction" |
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Replace air conditioning amplifier assembly |
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LIN communication system |
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No air inlet control |
Proceed to "BUS IC Communication Malfunction" |
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Proceed to "Air Inlet Damper Control Servo Motor Circuit" |
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Replace air conditioning amplifier assembly |
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No air flow mode control |
Proceed to "BUS IC Communication Malfunction" |
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Proceed to "Air Outlet Damper Control Servo Motor Circuit" |
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Replace air conditioning amplifier assembly |
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Engine coolant does not warm up quickly when engine is cold (PTC heater does not operate)* |
Proceed to "PTC Heater Circuit" |
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Proceed to "Generator Signal Circuit" |
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Check generator assembly |
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Replace air conditioning amplifier assembly |
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Engine idle up does not occur or is continuous |
Replace air conditioning amplifier assembly |
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Replace ECM |
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CAN communication system |
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Diagnostic trouble codes are not stored, and set mode is cleared when ignition switch is off |
Proceed to "Back-up Power Source Circuit" |
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Replace air conditioning amplifier assembly |
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- *: w/ PTC Heater
Test yourself
A quick Toyota 4Runner quiz: every answer comes with an explanation and a link to the manual page.