B1423

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1423: Pressure Sensor Circuit

DTC B1423 - Pressure Sensor Circuit

DESCRIPTION





The pressure switch to detect the refrigerant pressure is located in the sight glass side of the pipe on the high-pressure side. This DTC is output when the refrigerant pressure is either significantly low (below 196 kPa (2.0 kgf/cm2, 28 psi) or significantly high (over 3,140 kPa (32.0 kgf/cm2, 455 psi). Then the pressure switch sends appropriate signals to the air conditioning amplifier. The pressure switch has built-in switches to detect high and low pressure and is turned off when either is determined to be defective. The air conditioning amplifier continuously monitors the pressure switch signal after the power switch is turned ON (IG). It stops compressor control and outputs the DTC when it detects the signal indicating that the switch is turned OFF.






WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK REFRIGERANT PRESSURE
(a) Set the manifold gauge.
(b) Read the manifold gauge pressure when these conditions are established.

Test conditions:

- Temperature at the air inlet with the switch set at RECIRC is 30 to 35°C (86 to 95°F)
- Power switch ON (IG)
- Blower speed control switch at "HI" position
- Temperature control dial at "COOL" position
- Air conditioning switch ON
- Fully open doors

Standard pressure:
Pressure on high pressure side
1.37 to 1.57 MPa (13.9 to 16.0 kgf/cm2, 198 to 228 psi)
HINT: If the refrigerant pressure is below 196 kPa (2.0 kgf/cm2, 28 psi), the refrigerant amount in the air conditioning cycle may have decreased significantly for reasons such as a gas leakage.

NG -- INSPECT AND REPAIR AIR CONDITIONING CYCLE
OK -- Continue to next step.

2. CHECK AIR CONDITIONING OPERATION




(a) Disconnect the P1 pressure switch connector.
(b) Connect terminals 1 and 4 of the connector of the pressure switch on the vehicle wire harness side using a service wire.
(c) Turn the power switch ON (IG).
(d) Turn the air conditioning switch ON and check that the compressor is operated.
(e) Check that the compressor is not operated when disconnecting terminals 1 and 4 (that were connected in the prior step).
OK:
Terminals 1 and 4 connected: the compressor is operated
Terminals 1 and 4 disconnected: the compressor is not operated
OK -- REPLACE PRESSURE SWITCH
NG -- Continue to next step.

3. CHECK WIRE HARNESS (PRESSURE SWITCH - AIR CONDITIONING AMPLIFIER AND BODY GROUND)




(a) Disconnect the P1 pressure switch connector.
(b) Disconnect the A7 amplifier connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






Result





B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- REPAIR OR REPLACE HARNESS AND CONNECTOR
C -- REPLACE AIR CONDITIONING AMPLIFIER