Pinpoint Test N: The Heating Ventilation Air Conditioning (HVAC) Module Does Not Respond To The Scan Tool
WARNING: This page is about a different car, the 2008 Mercury Sable, 2008 Ford Taurus X, and 2008 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
- N1 CHECK THE VOLTAGE SUPPLY CIRCUITS FOR AN OPEN
- Key in OFF position.
- Disconnect: HVAC-EATC Module C228a or HVAC-EMTC module C2357a
- Key in ON position.
- Measure the voltage between the HVAC-EATC module C228a-12 or HVAC-EMTC module C2357a-12, circuit CBP37 (WH), harness side and ground; and between the HVAC-EATC module C228a-13 or HVAC-EMTC module C2357a-13, circuit SBP15 (WH/RD), harness side and ground.
- Are the voltages greater than 10 volts?
- YES : Go to N2.
- NO : VERIFY the SJB fuses 15 (10A) or 37 (10A) are OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
- N2 CHECK THE GROUND CIRCUIT FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the HVAC-EATC module C228a-23 or HVAC-EMTC module C2357a-23, circuit GD111 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
- YES : Go to N3.
- NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
- N3 CHECK THE MS-CAN CIRCUITS BETWEEN THE DLC AND THE HVAC MODULE FOR AN OPEN
- Measure the resistance between the HVAC-EATC module C228a-25 or HVAC-EMTC module C2357a-25, circuit VDB06 (GY/OG), harness side and the DLC C251-3, circuit VDB06 (GY/OG), harness side.
- Measure the resistance between the HVAC-EATC module C228a-26 or HVAC-EMTC module C2357a-26, circuit VDB07 (VT/OG), harness side and the DLC C251-11, circuit VDB07 (VT/OG), harness side.
- Are the resistances less than 5 ohms?
- YES : Go to N4.
- NO : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
- N4 CHECK FOR CORRECT HVAC MODULE OPERATION
- Disconnect all the HVAC module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the HVAC module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- YES : INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. CLEAR the DTCs. REPEAT the network test with the scan tool.
- NO : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.