EI07264 - Manual HVAC Performance, Temperature, Mode, A/C Does Not Cool, DTC B0228, B0413, B0423, B0433, B3779, B3782 (Engineering Information)

Important: 

Some customers may comment that the A/C blows hot air or is inoperative. They may also comment that they are unable to change the temperature or HVAC mode of the vehicle. In this instance, the actuator door defaults to full hot and defrost position.

GM Engineering is seeing an increase in HVAC control head and actuator warranty where the root cause is intermittent wiring connections at the actuator, control head or the right hand BEC.

GM has a need to obtain information BEFORE any repairs are made. If the customer's concern can be duplicated, perform the following inspections/steps:

1. Note the following information on the repair order:

1.1.	Describe the customer's concern -- be specific.

1.2.	List any/all DTCs and note whether the DTC is current or stored in history.

2. With the ignition OFF, disconnect the harness connector at the applicable actuator.
3. With the ignition OFF, test for less than 1 ohm between the low reference circuit terminal 7 and ground. Document the reading on the repair order.
4. With the ignition ON, test for 4.4-5.2 volts between the 5 volt reference circuit terminal 10 and ground. Document the reading on the repair order.
5. Verify the applicable scan tool parameter is less than 7 counts.
6. Install a 3A fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal 7. With the scan tool, verify the counts.
7. Verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
8. Test for 2.5 volts between the control circuit terminal 6 and ground. Document the reading on the repair order.
9. Install a DMM between the control circuit terminal 6 and ground. Command the actuator in each direction. Does the voltage on the control circuit change from 0 volts when commanding the actuator in one direction to 5 volts in the other direction, and return to 2.5 volts in the at rest state? If not, document the readings on the repair order.
10. Contact engineer Adam Freeman at 586-914-0404 and provide him with repair order information. Adam will provide information to proceed with correcting the customer's concern. If the engineer is not available to take the call, leave the following information:

- Technician Name, date and time of call

- Dealer Name, Dealer Code & Phone #

- VIN and Repair Order #

Important: If the engineer does not return the call within one (1) hour, continue to diagnose and repair following the information found in SI. Fax the front and back of the repair order to Adam Freeman (fax #: 248-685-4196).

For vehicles repaired under Engineering direction, use: