Nissan Leaf. Manual - part 784

B27C1 HEAT PUMP CONTROL UNIT

HAC-139

< DTC/CIRCUIT DIAGNOSIS >

[AUTO A/C (WITH HEAT PUMP)]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

B27C1 HEAT PUMP CONTROL UNIT

DTC Logic

INFOID:0000000010121848

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT

1. Turn power switch OFF.

2. Set the vehicle to READY.

3. Select “Self Diagnostic Result” of “HVAC” using CONSULT.

4. Check DTC.
Is DTC detected?

YES

>> Refer to 

HAC-139, "Diagnosis Procedure"

.

NO

>> Inspection End.

Diagnosis Procedure

INFOID:0000000010121849

Regarding Wiring Diagram information, refer to 

HAC-61, "Wiring Diagram"

.

1.

CHECK HEAT PUMP CONTROL UNIT POWER SUPPLY

1. Turn power switch ON

2. Check voltage between heat pump control unit harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> GO TO 2.

2.

CHECK A/C RELAY

Check A/C relay. Refer to 

EVC-385, "Diagnosis Procedure"

.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace malfunctioning components.

3.

CHECK HEAT PUMP CONTROL UNIT POWER SUPPLY CIRCUIT FOR OPEN

1. Turn power switch OFF.

2. Disconnect heat pump control unit.

3. Remove A/C relay.

4. Check continuity between heat pump control unit harness connector and A/C relay harness connector.

DTC

Items

(CONSULT screen terms)

DTC detection condition

Possible cause

B27C1

A/C AUTO AMP. LIN COMM

When there is a malfunction in the signal trans-
mitted from the heat pump control unit

• Heat pump control unit
• A/C auto amp.
• Harness or connectors

(Heat pump control unit circuit is 
open or shorted.)

+

−

Voltage

(Approx.)

Heat pump control unit

Connector

Terminal

M102

9

Ground

Battery voltage

HAC-140

< DTC/CIRCUIT DIAGNOSIS >

[AUTO A/C (WITH HEAT PUMP)]

B27C1 HEAT PUMP CONTROL UNIT

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair harness or connector.

4.

CHECK HEAT PUMP CONTROL UNIT POWER SUPPLY CIRCUIT FOR SHORT

Check continuity between heat pump control unit harness connector and ground.

Is the inspection result normal?

YES

>> Check intermittent incident. Refer to 

GI-53, "Intermittent Incident"

.

NO

>> Repair harness or connector.

5.

CHECK HEAT PUMP CONTROL UNIT GROUND CIRCUIT

1. Turn power switch OFF.

2. Disconnect heat pump control unit connector.

3. Check continuity between heat pump control unit harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Repair harness or connector.

6.

CHECK HEAT PUMP CONTROL UNIT COMMUNICATION LINE FOR OPEN

1. Disconnect A/C auto amp. connector.

2. Check continuity between heat pump control unit harness connector and A/C auto amp. harness connec-

tor.

NOTE:

Check for any adhering foreign substances, cracking, or damage on the heat pump control unit terminal

and A/C auto amp. harness connector terminal.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Repair harness or connector.

7.

CHECK HEAT PUMP CONTROL UNIT COMMUNICATION LINE FOR SHORT

Check continuity between heat pump control unit harness connector and ground.

Is the inspection result normal?

Heat pump control unit

A/C relay

Continuity

Connector

Terminal

Connector

Terminal

M102

9

E52

5

Yes

Heat pump control unit

−

Continuity

Connector

Terminal

M102

9

Ground

No

Heat pump control unit

−

Continuity

Connector

Terminal

M102

16

Ground

Yes

Heat pump control unit

A/C auto amp.

Continuity

Connector

Terminal

Connector

Terminal

M102

1

M55

40

Yes

Heat pump control unit

−

Continuity

Connector

Terminal

M102

1

Ground

No

B27C1 HEAT PUMP CONTROL UNIT

HAC-141

< DTC/CIRCUIT DIAGNOSIS >

[AUTO A/C (WITH HEAT PUMP)]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

YES

>> GO TO 8.

NO

>> Repair harness or connector.

8.

PERFORM DTC CONFIRMATION PROCEDURE

Perform DTC confirmation procedure. Refer to 

HAC-139, "DTC Logic"

.

Is DTC B27C1 detected?

YES

>> Replace heat pump control unit. Refer to 

HAC-188, "Removal and Installation"

.

NO

>> Inspection End.

HAC-142

< DTC/CIRCUIT DIAGNOSIS >

[AUTO A/C (WITH HEAT PUMP)]

B27C2, B27C3 PTC HEATER OUTLET AIR TEMPERATURE SENSOR

B27C2, B27C3 PTC HEATER OUTLET AIR TEMPERATURE SENSOR

DTC Logic

INFOID:0000000010121850

DTC DETECTION LOGIC 

NOTE:

• If DTC is displayed along with DTC U1000, first perform the trouble diagnosis for DTC U1000. Refer to 

HAC-

87, "DTC Logic"

.

• If DTC is displayed along with DTC U1010, first perform the trouble diagnosis for DTC U1010. 

HAC-88,

"DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT

1. Turn power switch OFF.

2. Set the vehicle to READY.

3. Operate the automatic air conditioning system.

4. Set the temperature to full hot and wait at least 2 seconds.

5. Select “Self Diagnostic Result” of “HVAC” using CONSULT.

6. Check DTC.
Is DTC detected?

YES

>> Refer to 

HAC-148, "Diagnosis Procedure"

.

NO

>> Inspection End.

Diagnosis Procedure

INFOID:0000000010121851

Regarding Wiring Diagram information, refer to 

HAC-61, "Wiring Diagram"

.

1.

CHECK PTC HEATER OUTLET AIR TEMPERATURE SENSOR VOLTAGE SIGNAL

1. Turn power switch ON.

2. Operate the automatic air conditioning system.

3. Check voltage between A/C auto amp. harness connector terminals.

Is the inspection result normal?

DTC

Items

(CONSULT screen terms)

DTC detection condition

Possible cause

B27C2

PTC OUT AIR TEMP SENS

The PTC heater outlet air temperature sensor 
recognition temperature is too low [less than 

−

42

°C (−44°F)].

• PTC heater outlet air temperature 

sensor

• A/C auto amp.
• Harness or connectors

(The sensor circuit is open or short-
ed.)

B27C3

The PTC heater outlet air temperature sensor 
recognition temperature is too high [more than 
200

°C (392°F)].

A/C auto amp.

Test condition

Voltage signal

connector

+

−

Terminal

M55

17

10

• Power switch ON
• When air conditioner is op-

erating

JSIIA1778ZZ