Pinpoint Test G : The HVAC (Heating, Ventilation And Air Conditioning) Module Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2018 Ford Fiesta. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings.

G1 CHECK THE HVAC (HEATING, VENTILATION AND AIR CONDITIONING) MODULE VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Disconnect HVAC module C228A.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C228A-10	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to G2

No	VERIFY the CJB fuse 12 (7.5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to OEM Electrical Wiring Diagram Introduction to identify the possible causes of the circuit short.

G2 CHECK THE HVAC (HEATING, VENTILATION AND AIR CONDITIONING) MODULE GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect negative battery cable.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C228A-3	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to G3

No	REPAIR the circuit. CONNECT the negative battery cable.

G3 CHECK THE MS-CAN (MEDIUM SPEED-CONTROLLER AREA NETWORK) CIRCUITS BETWEEN THE HVAC (HEATING, VENTILATION AND AIR CONDITIONING) MODULE AND THE DLC (DATA LINK CONNECTOR) FOR AN OPEN

Measure:

Positive Lead	Measurement / Action	Negative Lead
C228B-4	Courtesy of FORD MOTOR COMPANY	C251-3
C228B-5	Courtesy of FORD MOTOR COMPANY	C251-11

Are the resistances less than 3 ohms?

Yes	CONNECT the negative battery cable. GO to G4

No	REPAIR the circuit in question. CONNECT the negative battery cable.

G4 CHECK FOR CORRECT HVAC (HEATING, VENTILATION AND AIR CONDITIONING) MODULE OPERATION

Ignition OFF.

Disconnect and inspect the HVAC module connectors.

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

Reconnect the HVAC module 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 Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new HVAC 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.