Toyota CH-R Service Manual: Pressure Sensor Circuit (B1423)

DESCRIPTION

This DTC is stored if refrigerant pressure on the high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less)*1, (195 kPa (2.0 kgf/cm2, 28 psi) or less)*2 or extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more)*1, (2812 kPa (28.7 kgf/cm2, 408 psi) or more)*2. The air conditioner pressure sensor, which is installed to the high pressure side pipe to detect refrigerant pressure, sends a refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts this signal to a pressure value according to the sensor characteristics and uses it to control the compressor.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Memory
B1423	Pressure Sensor Circuit	Any of the following conditions is met: Open in air conditioner pressure sensor circuit (Only when the outside temperature is 5 °C (41°F) or more) Short in air conditioner pressure sensor circuit (Only when the outside temperature is 5 °C (41°F) or more) for HFC-134a (R134a): Refrigerant pressure on high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less) or extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more) (Only when the outside temperature is 5 °C (41°F) or more) for HFO-1234yf (R1234yf): Refrigerant pressure on high pressure side is extremely low (195 kPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (2812 kPa (28.7 kgf/cm2, 408 psi) or more) (Only when the outside temperature is 5 °C (41°F) or more)	Air conditioner pressure sensor Harness or connector between air conditioner pressure sensor and air conditioning amplifier assembly Air conditioning amplifier assembly Cooler expansion valve (blocked, stuck) Cooler condenser assembly (blocked, deterioration of cooling capacity due to dirt) Cooler dryer (moisture in the refrigerant cycle cannot be absorbed) Cooling fan system (cooler condenser assembly cannot be cooled down) Air conditioning system (leaks, blocked)	-

DTC Detection Conditions

		Vehicle Condition
		Pattern 1	Pattern 2	Pattern 3	Pattern 4
Diagnosis Condition	Ignition switch ON	○	○	○	○
	Only when the outside temperature is 5°C (41°F) or more.	○	○	○	○
Malfunction Status	Open in air conditioner pressure sensor circuit	○	-	-	-
	Short in air conditioner pressure sensor circuit	-	○	-	-
	for HFC-134a (R134a): Refrigerant pressure on high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi)	-	-	○	-
	for HFO-1234yf (R1234yf): Refrigerant pressure on high pressure side is extremely low (195 kPa (2.0 kgf/cm2, 28 psi) or less)	-	-	○	-
	for HFC-134a (R134a): Refrigerant pressure on high pressure side is extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more)	-	-	○	○
	for HFO-1234yf (R1234yf): Refrigerant pressure on high pressure side is extremely high (2812 kPa (28.7 kgf/cm2, 408 psi) or more)	-	-	-	○
Detection Time		4 seconds or more	4 seconds or more	4 seconds or more	4 seconds or more
Number of Trips		1 trip	1 trip	1 trip	1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the air conditioner pressure sensor connector.

*a Front view of wire harness connector (to Air Conditioner Pressure Sensor)

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A52-1 (+) - A52-3 (-)	Ignition switch ON	4.75 to 5.25 V

NG

GO TO STEP 16

OK

2.	INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Reconnect the A52 air conditioner pressure sensor connector.

(b) Remove the air conditioning amplifier assembly with the connectors still connected.

(c) Measure the voltage according to the value(s) in the table below.

*a

Component with harness connected (Air Conditioning Amplifier Assembly)

-

-

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
F72-33 (PRE) - Body ground	Ignition switch ON (A/C switch: off)	0.74 to 4.61 V

HINT:

If the result is not as specified, there may be a malfunction in the air conditioning amplifier assembly, air conditioner pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

NG

GO TO STEP 10

OK

3.	INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)

(a) Measure the voltage when the following conditions are met.

Measurement Condition:

Item	Condition
Vehicle doors	Fully open
Temperature setting	MAX COLD
Blower speed	HI
A/C switch	On
Recirculation/fresh switch	RECIRCULATION
Interior temperature	25 to 35°C (77 to 95°F)
Engine speed	2000 rpm

HINT:

When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the cooler (ambient temp. sensor) thermistor and the No. 1 cooler thermistor (evaporator temperature sensor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

(1) Measure the voltage according to the value(s) in the table below.

*a

Component with harness connected (Air Conditioning Amplifier Assembly)

-

-

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
F72-33 (PRE) - Body ground	Ignition switch ON (A/C switch: On)	0.74 to 4.61 V

Result	Proceed to
OK (When troubleshooting according to DTC)	A
OK (When troubleshooting according to Problem Symptoms Table)	B
NG	C

A

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

B

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

4.	INSPECT COOLING FAN SYSTEM

(a) Check if the cooling fan operates normally.

Click here

Result	Proceed to
OK	A
NG	B

B

GO TO COOLING FAN SYSTEM

A

5.	CHARGE SYSTEM WITH REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the air conditioning system.

(c) Add an appropriate amount of refrigerant.

HINT:

If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

NEXT

6.	RECHECK FOR DTC

(a) Recheck for the DTC when the following conditions are met.

Measurement Condition:

Item	Condition
Vehicle doors	Fully open
Temperature setting	MAX COLD
Blower speed	HI
A/C switch	On
Recirculation/fresh switch	RECIRCULATION
Interior temperature	25 to 35°C (77 to 95°F)
Engine speed	2000 rpm

Body Electrical > Air Conditioner > Trouble Codes

NOTICE:

If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

Result	Proceed to
DTC B1423 is output	A
DTC B1423 is not output	B

B

REPLACE COOLER CONDENSER ASSEMBLY

A

7.	REPLACE COOLER EXPANSION VALVE

(a) Replace the cooler expansion valve with a new one.

Click here

HINT:

Replace the cooler expansion valve with a new one because the cooler expansion valve is either stuck or clogged.

NEXT

8.	CHARGE SYSTEM WITH REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the air conditioning system.

(c) Add an appropriate amount of refrigerant.

HINT:

If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

NEXT

9.	RECHECK FOR DTC

(a) Recheck for the DTC when the following conditions are met.

Measurement Condition:

Item	Condition
Vehicle doors	Fully open
Temperature setting	MAX COLD
Blower speed	HI
A/C switch	On
Recirculation/fresh switch	RECIRCULATION
Interior temperature	25 to 35°C (77 to 95°F)
Engine speed	2000 rpm

Body Electrical > Air Conditioner > Trouble Codes

NOTICE:

If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

Result	Proceed to
DTC B1423 is not output	A
DTC B1423 is output	B

A

END

B

CLEAN OR REPLACE COOLER CONDENSER ASSEMBLY

10.	CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR)

(a) Disconnect the A52 air conditioner pressure sensor connector.

(b) Disconnect the F72 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A52-2 (PR) - F72-33 (PRE)	Always	Below 1 Ω
A52-2 (PR) or F72-33 (PRE) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

11.	INSPECT FOR AIR CONDITIONING SYSTEM LEAK

(a) Install a manifold gauge set.

(b) Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.

(c) Evacuate the air conditioning system and check that vacuum can be maintained.

OK:

Vacuum can be maintained in the air conditioning system.

HINT:

If vacuum cannot be maintained in the air conditioning system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the air conditioning system.

NG

GO TO STEP 15

OK

12.	CHARGE SYSTEM WITH REFRIGERANT

(a) Use a refrigerant recovery unit to recover refrigerant.

(b) Evacuate the air conditioning system.

(c) Add an appropriate amount of refrigerant.

HINT:

If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

NEXT

13.	RECHECK FOR DTC

(a) Recheck for the DTC when the following conditions are met.

Measurement Condition:

Item	Condition
Vehicle doors	Fully open
Temperature setting	MAX COLD
Blower speed	HI
A/C switch	On
Recirculation/fresh switch	RECIRCULATION
Interior temperature	25 to 35°C (77 to 95°F)
Engine speed	2000 rpm

Body Electrical > Air Conditioner > Trouble Codes

NOTICE:

If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

HINT:

When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the cooler (ambient temp. sensor) thermistor and the No. 1 cooler thermistor (evaporator temperature sensor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

Result	Proceed to
DTC B1423 is output	A
DTC B1423 is not output	B

NOTICE:

If the DTC was stored to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leaks. The root cause of excessive refrigerant may be adding too much refrigerant when the level was insufficient. Therefore, identify and repair the area where refrigerant leaks from as necessary.

B

END

A

14.	INSPECT AIR CONDITIONER PRESSURE SENSOR

(a) Install a manifold gauge set.

(b) Reconnect the A52 air conditioner pressure sensor connector.

(c) Remove the air conditioning amplifier assembly with the connectors still connected.

(d) Turn the ignition switch ON.

(e) Measure the voltage according to the value(s) in the table below.

*a

Component with harness connected (Air Conditioning Amplifier Assembly)

-

-

Standard Voltage:

Tester Connection	Condition	Specified Condition
F72-33 (PRE) - F72-32 (SG-2)	Refrigerant pressure: Normal pressure (less than 3025 kPa (30.8 kgf/cm2, 439 psi) and more than 176 kPa (1.8 kgf/cm2, 26 psi))	0.74 to 4.61 V

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPLACE AIR CONDITIONER PRESSURE SENSOR

15.	REPAIR AIR CONDITIONING SYSTEM LEAK

(a) Identify the area where refrigerant leaks from.

(b) Repair the identified area of the air conditioning system.

(c) Evacuate the air conditioning system.

Result	Proceed to
for HFC-134a (R134a)	A
for HFO-1234yf (R1234yf)	B

A

CHARGE SYSTEM WITH REFRIGERANT

B

CHARGE SYSTEM WITH REFRIGERANT

16.	CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR)

(a) Disconnect the F72 air conditioning amplifier assembly connector.

(b) Disconnect the A52 air conditioner pressure sensor connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A52-1 (+) - F72-34 (S5-3)	Always	Below 1 Ω
A52-3 (-) - F72-32 (SG-2)	Always	Below 1 Ω
A52-1 (+) or F72-34 (S5-3) - Body ground	Always	10 kΩ or higher
A52-3 (-) or F72-32 (SG-2) - Body ground	Always	10 kΩ or higher

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR