davidh11

The A/C in my 2007 tahoe usually works just fine, but here recently it will all of the sudden start blowing hot. The little snowflake symbol goes off and when I attempt to push the button to turn it back on, it blinks twice and stays off. It blows hot in the front and in the back. This is the third time it has done this in a month. I don't think that it is the freon or a leak because when it works, it blows cold. The last time it did this I pulled out all 5 or 6 of the HVAC fuses, let them sit out for approx. 1 minute and reinstalled them. When I turned the tahoe back on the a/c worked fine. Is there a sensor, switch, or something that could be going out? Thank you for the help.

in2pro

Here are a couple of items I found...


#07-01-38-006: Information for Vehicles with HVAC Control Module A/C Indicator Blinking Due to Low Battery State of Charge - (Aug 20, 2007)


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)




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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 Powertrain.

• Select Engine Control Module (ECM).

• Select Data Display.

• 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.



Actuator Recalibration
When replacing the HVAC control module it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC control module be sure to perform the following:


Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.

in2pro

Sounds like when you are pulling the fuses you are causing it to re calibrate....
Why is it always getting un-calibrated?

ChevyEsau

did you find out what senors the problem is? I'm having the same issue. i changed the upper lower switch, the rwo temp se. i did notnsors. i filed the freon. i did notice when i filled the freon the light stop blinking but no cold air

repairman54

Needs a proper refrigerant charge which is done by weight of Freon into a vacuumed out system. Juicing up the system with little cans is just a guess and may turn off the blinking light indicator of a low system but still be a low charge with poor cooling.