| Subject: | Information For Vehicles with HVAC Control Module A/C Indicator Blinking Due to Low Battery State of Charge |
| Models: | 2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe |
| 2007-2008 GMC Sierra, Yukon, Yukon XL |
| with Manual Temperature Control HVAC System (RPO CJ3) |
An Air Condition (A/C) button on the Heating, Ventilation and Air Conditioning (HVAC) control module may blink when the A/C system is activated. The blinking indicator will turn to a solid light after cycling the A/C button or ignition key.
This condition may be caused by a low battery state of charge on a PREVIOUS
ignition key cycle. This condition may be due to situations were an unsold vehicle is parked for long periods of time as part of a dealership's unsold
inventory. The A/C indicator begins to flash If the battery voltage falls below 9.5 volts. The low voltage condition may occur during an engine crank or if the vehicle is parked and a normal battery state of charge is not maintained.
Do This
| Don't Do This
|
Run the vehicle to charge the battery or connect a battery charger. (If the charging system is operating as designed , the battery surface charge should indicate 12+ volts.)
| Do Not Replace the battery, HVAC control module or ECM.
|
If the A/C indicator continues to blink, use the Tech 2® to help determine the cause.
| • | Connect the Tech 2 and build the vehicle. |
| • | Select Engine Control Module (ECM). |
| • | Select Cooling/HVAC data. |
| • | Make sure that there has been an A/C request signal. |
| • | History should indicate any causes. |
If necessary, refer to SI for further information on HVAC system diagnostic procedures.
