Pinpoint Test O: B1B71:11, B1B71:15

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Wiring Diagrams AUTOMATIC CLIMATE CONTROL SYSTEM for schematic and connector information.

Normal Operation and Fault Conditions

Evaporator Temperature Sensor, REFER to: Climate Control System - Vehicles With: Dual Automatic Temperature Control (DATC) - System Operation and Component Description .

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
HVAC B1B71:11	Evaporator Temperature Sensor: Circuit Short To Ground	Module senses lower than expected voltage on the sensor feedback circuit, indicating a short to ground.
HVAC B1B71:15	Evaporator Temperature Sensor: Circuit Short To Battery Or Open	Module senses greater than expected voltage on the sensor feedback circuit, indicating a short to voltage or an open circuit or sensor.

Possible Sources

Wiring, terminals or connectors
Evaporator temperature sensor
HVAC control module

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

O1 CHECK THE EVAPORATOR TEMPERATURE SENSOR CIRCUITS FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect HVAC control module C228A and C228B.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C228A-2	Courtesy of FORD MOTOR COMPANY	Ground
C228A-19	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit in question.

GO to O2

O2 CHECK THE EVAPORATOR TEMPERATURE SENSOR CIRCUITS FOR A SHORT TO GROUND

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C228A-2	Courtesy of FORD MOTOR COMPANY	Ground
C228A-19	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to O3

No	REPAIR the circuit in question.

O3 CHECK THE EVAPORATOR TEMPERATURE SENSOR CIRCUITS FOR AN OPEN

Disconnect Evaporator temperature sensor C296.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C228A-2	Courtesy of FORD MOTOR COMPANY	C296-1
C228A-19	Courtesy of FORD MOTOR COMPANY	C296-2

Are the resistances less than 3 ohms?

Yes

GO to O4

No	REPAIR the circuit in question.

O4 CHECK THE EVAPORATOR TEMPERATURE SENSOR CIRCUITS FOR A SHORT TOGETHER

Measure:

Positive Lead	Measurement / Action	Negative Lead
C296-1	Courtesy of FORD MOTOR COMPANY	C296-2

Is the resistance greater than 10, 000 ohms?

Yes	INSTALL a new evaporator temperature sensor. REFER to: Evaporator Temperature Sensor . TEST the system for normal operation. If the concern is still present, GO to O5

No	REPAIR the circuits.

O5 CHECK FOR CORRECT HVAC (HEATING, VENTILATION AND AIR CONDITIONING) CONTROL MODULE OPERATION

Ignition OFF.

Disconnect and inspect all HVAC control module electrical connectors (if not previously disconnected).

Repair:
- corrosion (install new connector or terminal - clean module pins)
- damaged or bent pins - install new terminals or pins
- pushed-out pins - install new pins as necessary

Connect all HVAC control module electrical connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes

CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new HVAC control module. REFER to: Heating, Ventilation and Air Conditioning (HVAC) Control Module .

No	The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.