HVAC - Diagnostics: Diagnosis Toyota Sequoia I

HOW TO PROCEED WITH TROUBLESHOOTING

Perform troubleshooting in accordance with the procedure.

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1. Warning For A/C Compressor Lock If compressor lock occurs during A/C operation, the A/C switch indicator on the A/C control assembly starts blinking. When this occurs, check for compressor lock (see «DTC 22 COMPRESSOR LOCK SENSOR CIRCUIT»(ref-170283-S33889089902005012600000) and «DIAGNOSTIC TROUBLE CODE CHART»(ref-170283-S33889089902005012600000) ) using diagnosis trouble code check then proceed to inspect the circuit or the component. Compressor lock sensor circuit. See «DTC 22 COMPRESSOR LOCK SENSOR CIRCUIT»(ref-170283-S25153010552005012600000).
2. List Of Operation Methods: By operating each of the A/C control switches as shown in the diagram below, it is possible to enter the diagnosis check mode.
3. Indicator Check: Turn the ignition switch to on while pressing the A/C control AUTO switch and R/F SW simultaneously. NOTE: After the indicator check is ended, the diagnostic trouble code check begins automatically. Press the OFF switch when desiring to cancel the check mode. Check that all the indicators light up and go off at 1 second intervals 4 times in succession.
4. DTC Check (Sensor Check) Perform an indicator check. After the indicator check is completed, the system enters the DTC check mode automatically. Read the DTC displayed on the panel. Refer to the list of DTCs, see «DIAGNOSTIC TROUBLE CODE CHART»(ref-170283-S33889089902005012600000), when reading the DTCs (DTCs are out put at the temperature display (Scheme 7)). If the slower display is desired, press the DEF. SW and change it to step operation. Each time the Temp. Control switch is pressed, the display changes by 1 step.
5. Clearing DTC: Pull out the DOME fuse in engine room J/B for 10 sec. or longer to clear the diagnostic DTC's memory. After reinserting the fuse, check that the normal code is output.
6. Actuator Check: After entering the sensor check mode, press the R/F switch. NOTE: Code are displayed in order from the smaller to the larger numbers. To cancel the check mode, press the OFF switch. Since each damper, motor and relay automatically operates at 1 second intervals beginning in order from 20 in the temperature display, check the temperature and air flow visually and by hand. If a slower display is desired, press the DEF. (Fr.) switch and change it to step operation. Each time the DEF. (Fr.) switch is pressed, the display changes by 1 step.

DIAGNOSTIC TROUBLE CODE CHART

If malfunction code is displayed during the DTC check, check the circuit listed for that code in the table below (Proceed to the procedure given for that circuit).

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DIAGNOSTIC TROUBLE CODES (DTC) LIST

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Circuit Description

This sensor detects the temperature inside the cabin and sends the appropriate signals to the integration control and panel.

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This sensor detects the ambient temperature and sends the appropriate signals to the integration control and panel.

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This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the integration control and panel.

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This sensor detects the engine coolant temperature and sends the appropriate signals to the integration control and panel. These signals are used for warm up control when engine is cold.

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Inspection Procedure

1. Does DTC P0115 output? YES: Go to engine troubleshooting. See «HOW TO PROCEED WITH TROUBLESHOOTING»(ref-174490-S03150340642005040500000) . NO: Go to next step.
2. Check harness and connector between ECM and integration control and panel. NG: Repair or replace harness or connector. OK: Check and replace integration control and panel.

This sensor detects the rear evaporator temperature and sends the appropriate signals to the integration control and panel.

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This sensor detects the temperature inside the cabin and sends the appropriate signals to the integration control and panel.

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A photo diode in the solar sensor detects solar radiation and sends signals to the integration control and panel.

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This sensor sends 1 pulse per engine revolution to the integration control and panel.

If the number ratio of the compressor speed divided by the engine speed is smaller than a predetermined value, the integration control and panel turns the compressor OFF. And, the indicator flashes at about 1 second intervals.

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The pressure switch sends the appropriate signals to the intgration control and panel when the A/C refrigerant pressure drops too low or rises too high. When the integration control and panel receives these signals, it outputs signals via the integration control and panel to switch OFF the compressor relay and turns the magnetic clutch OFF.

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This sensor detects the position of the air mix damper and sends the appropriate signals to the integration control and panel.

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The position sensor is built into the air mix damper control servomotor assembly.

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This sensor detects the position of the air inlet damper and sends the appropriate signals to the integration control and panel.

The position sensor is built into the air inlet damper control servomotor assembly.

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This sensor detects the position of the air mix damper and sends the appropriate signals to the integration control and panel.

The position sensor is built into the water valve damper control servomotor assembly.

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The front air mix damper control servomotor is controlled by the integration control and panel and moves the air mix damper to the desired position.

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The air inlet damper control servomotor is controlled by the integration control and panel and moves the air inlet damper to the desired position.

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The water valve damper control servomotor is controlled by the integration control and panel and moves the water valve damper to the desired position.

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This is the power source for the integration control and panel (contains the ECU) and servomotors, etc.

This is the back up power source for the integration control and panel. Power is supplied even when the ignition switch is off and is used for diagnostic trouble code memory, etc.

This circuit supplies power to the integration control and panel. It supplies power to the illumination for the clock.

This integration control and panel monitors the vehicle speed through signals sent from the speed sensor.

The integration control and panel uses these signals to revice the ambient temperature sensor signal.

1. Check Operation Of Speedometer Check: Check that the tachometer operates normally. NG: Proceed to «COMBINATION METER»(ref-174958) NG: Go to next step.
2. Check Harness And Connector Between Integration Control And Panel And Combination Meter NG: Repair or replace harness or connector. OK: Check and replace integration control and panel.

This integration control and panel monitors the engine speed through signals sent from the igniter. The integration control and panel uses these signals and compressor speed signals to detect the compressor lock condition.

1. Check Operation Of Tachometer Check: Check that the tachometer operates normally. NG: Proceed to «COMBINATION METER»(ref-174958) . OK: Go to next step.
2. Check Harness And Connector Between Integration Control And Panel And ECM NG: Repair or replace harness or connector. OK: Go to next step.
3. Check Harness And Connector Between Integration Control And Panel And Combination Meter NG: Repair or replace harness or connector. OK: Check and replace integration control and panel.

The blower motor is operated by signals from the integration control and panel. Blower motor speed signals are transmitted by changes in the Duty Ratio.

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Duty Ratio

The duty ratio is the ratio of the period of continuity in one cycle. For example, if A is the period of continuity in one cycle, and B is the period of non-continuity, then.

This is the power source for blower motor.

The integration control and panel outputs the magnetic clutch ON signal from terminal AC1 to the ECM. When the ECM receives this signal, it sends a signal from terminal MGC and switches the A/C magnetic clutch relay ON, thus turning on the A/C magnetic clutch.