PINPOINT TEST G : The Heating Ventilation Air Conditioning (HVAC) Module Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2016 Ford Expedition. 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. Refer to Battery, Mounting and Cables .

G1 CHECK THE MS-CAN TERMINATION RESISTANCE

Ignition OFF.

Disconnect: Negative Battery Cable.

Measure:

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

Is the resistance between 54 and 66 ohms?

Yes	GO to G3.
No	GO to G2.

G2 CHECK THE MS-CAN CIRCUITS BETWEEN THE HVAC MODULE AND THE DLC FOR AN OPEN

Disconnect: HVAC module C2357A (EMTC) or C228A (EATC).

Measure:

EMTC

Positive Lead	Measurement / Action	Negative Lead
C2357A-25	Courtesy of FORD MOTOR COMPANY	C251-3
C2357A-26	Courtesy of FORD MOTOR COMPANY	C251-11

EATC

Positive Lead	Measurement / Action	Negative Lead
C228A-12	Courtesy of FORD MOTOR COMPANY	C251-3
C228A-13	Courtesy of FORD MOTOR COMPANY	C251-11

Are the resistances less than 3 ohms?

Yes	GO to G5.
No	REPAIR the circuit in question.

G3 CHECK THE HVAC MODULE VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Connect: Negative Battery Cable.

Ignition ON.

Measure:

EMTC

Positive Lead	Measurement / Action	Negative Lead
C2357A-12	Courtesy of FORD MOTOR COMPANY	Ground
C2357A-13	Courtesy of FORD MOTOR COMPANY	Ground

EATC

Positive Lead	Measurement / Action	Negative Lead
C228A-26	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	GO to G4.
No	VERIFY the BCM fuse 46 (10A) or BCM fuse 35 (5A) (EMTC) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction to identify the possible causes of the circuit short.

G4 CHECK THE HVAC MODULE GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: Negative Battery Cable.

Disconnect: EMTC C2357C or EATC C228C

Measure:

EMTC

Positive Lead	Measurement / Action	Negative Lead
C2357A-23	Courtesy of FORD MOTOR COMPANY	Ground

Positive Lead	Measurement / Action	Negative Lead
C2357C-1	Courtesy of FORD MOTOR COMPANY	Ground

EATC

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

Positive Lead	Measurement / Action	Negative Lead
C228C-8	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes	CONNECT the negative battery cable. GO to G5.
No	REPAIR the circuit.

G5 CHECK FOR CORRECT HVAC MODULE OPERATION

Ignition OFF.

Disconnect and inspect the HVAC module connectors and related in-line connectors.

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

Reconnect the HVAC module connectors and related in-line connectors. Make sure they seat and latch correctly.

Operate the system and verify the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, discontinue this test and follow TSB instructions. If no TSBs address this concern, INSTALL a new HVAC module. REFER to Climate Control .
No	The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.