Up to 08/2009

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1479/79: Flow Sensor Circuit
B1479/79 - Flow Sensor Circuit

DESCRIPTION

The A/C mass flow sensor, which is mounted on the A/C compressor, is used to detect the amount of refrigerant flow. The A/C mass flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the A/C amplifier. The voltage value sent from the A/C mass flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The A/C amplifier supplies 5 V to the A/C mass flow sensor and monitors changes in the voltage value sent from the A/C mass flow sensor. The A/C amplifier then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Data List.

(e) Check the value(s) by referring to the table below.

Air Conditioner





OK:

The display is as specified in the Normal Condition column.

Result:





C -- REPLACE A/C COMPRESSOR (A/C MASS FLOW SENSOR)

B -- REPLACE A/C AMPLIFIER
A -- Continue to next step.

2. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Data List.

(e) Check the value(s) by referring to the table below.

Air Conditioner





Result:





B -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures
A -- Continue to next step.

3. REPLACE A/C COMPRESSOR (A/C MASS FLOW SENSOR)

(a) Replace the A/C compressor (A/C mass flow sensor) Removal.

HINT
Since the A/C compressor (A/C mass flow sensor) cannot be inspected while it is removed from the vehicle, replace the A/C compressor (A/C mass flow sensor) with a new or a known good one and check that the condition returns to normal.

(b) Check for the DTC.

Result:





B -- CHECK HARNESS AND CONNECTOR (A/C COMPRESSOR (A/C MASS FLOW SENSOR) - A/C AMPLIFIER)

A -- END

4. CHECK HARNESS AND CONNECTOR (A/C COMPRESSOR (A/C MASS FLOW SENSOR) - A/C AMPLIFIER)

(a) Disconnect the A/C amplifier connector.





(b) Measure the resistance according to the value(s) in the table below.





Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE A/C AMPLIFIER