Auto Climate Control

fbachman · August 28, 2009

Have the auto climate control set to 71... starts out fine blowing on high to cool off interior. Then, it reaches an interior temp to where it switches from recirc to outside air, fan slows down, all as expected.

Pull up at a light, and notice the fan speed oscillating, and no air from the vents. investigate. System appears to be "locked" in defrost. No air from window vents, eventhough control panel shows single "vent" arrow.

Manually switching to vents, floor, defrost and back does nothing --- arrow on display is moving around.... air only from defrost vents.

Pull over, shut engine off, restart engine, system appears to re-boot, and it works correctly again.

Once I even heard what I thought was an oscilalting solenoid somewhere under the dash on the driver's side, right above where my knees are below the dash.

Has happened 2-3 times now. I guess I'll report that when they re-finish my wheels and see what may be happening there.

Anyone else had a tempramental auto-climate control?????

Johnson8537 · September 28, 2009

Have the auto climate control set to 71... starts out fine blowing on high to cool off interior. Then, it reaches an interior temp to where it switches from recirc to outside air, fan slows down, all as expected.

Pull up at a light, and notice the fan speed oscillating, and no air from the vents. investigate. System appears to be "locked" in defrost. No air from window vents, eventhough control panel shows single "vent" arrow.

Manually switching to vents, floor, defrost and back does nothing --- arrow on display is moving around.... air only from defrost vents.

Pull over, shut engine off, restart engine, system appears to re-boot, and it works correctly again.

Once I even heard what I thought was an oscilalting solenoid somewhere under the dash on the driver's side, right above where my knees are below the dash.

Has happened 2-3 times now. I guess I'll report that when they re-finish my wheels and see what may be happening there.

Anyone else had a tempramental auto-climate control?????

Nope... but I don't like the Auto Feature on mine. ( Our Acura with dual climate has Auto and it does both heat and cool.)

The Silverado on Auto i have to hit the AC button if i want it to get cold???

And if i crank up the heat and forget about the AC button.. I am running HOT AIR and AC???

Seems silly to me? I would think AUTO woudl be automatic not having to select HOT or Cold just a disired temp and forget it.

Example if i want tit to be 75 in the truck If it is hotter than the AC shoudl kick it down to 75. If it is colder than the heater should kick it up to 75. Seems simple to me?

VMax2007 · September 28, 2009

Example if i want tit to be 75 in the truck

I prefer them a little younger, but to each his own.

txab · September 28, 2009

Have you tried doing a system re-set by pulling the fuses for the hvac or by disconnecting the battery for a bit?

At least give it a shot.

http://www.gm-trucks.com/forums/index.php?...mp;#entry897550

fbachman · September 28, 2009

Have you tried doing a system re-set by pulling the fuses for the hvac or by disconnecting the battery for a bit?

At least give it a shot.

http://www.gm-trucks.com/forums/index.php?...mp;#entry897550

Funny this post should resurface today....

Actually, just the other day, it did it again while I was fairly close to my dealer. Called them, went in, they were waiting for me with the scan tool and pulled the following code(s)

B3779 ---

Symptom 5:

fbachman · September 28, 2009

Have you tried doing a system re-set by pulling the fuses for the hvac or by disconnecting the battery for a bit?

At least give it a shot.

http://www.gm-trucks.com/forums/index.php?...mp;#entry897550

Funny this post should resurface today....

Actually, just the other day, it did it again while I was fairly close to my dealer. Called them, went in, they were waiting for me with the scan tool and pulled the following code(s)

B3779 ---

Symptom 5:

fbachman · September 28, 2009

Have you tried doing a system re-set by pulling the fuses for the hvac or by disconnecting the battery for a bit?

At least give it a shot.

http://www.gm-trucks.com/forums/index.php?...mp;#entry897550

Funny this post should resurface today....

Actually, just the other day, it did it again while I was fairly close to my dealer. Called them, went in, they were waiting for me with the scan tool and pulled the following code(s) while the system was stuck in defrost mode (again)

B3779 ---

Symptom 5: Short Cirquit

SYmptom 61: Air FLow Control Flow Actuator Stuck

which is consistent to what I was experienceing. When the problem goes on hiatus, the code, of course is not active. I believe it gets thrown into history.

But, in any case, looks like the problem is diagnosed, and the truck is in TODAY to get this taken care of....

EDIT: WOW ... looks like a parital double post.... sorry, not sure what I did....

brims · September 28, 2009

Have the auto climate control set to 71... starts out fine blowing on high to cool off interior. Then, it reaches an interior temp to where it switches from recirc to outside air, fan slows down, all as expected.

Pull up at a light, and notice the fan speed oscillating, and no air from the vents. investigate. System appears to be "locked" in defrost. No air from window vents, eventhough control panel shows single "vent" arrow.

Manually switching to vents, floor, defrost and back does nothing --- arrow on display is moving around.... air only from defrost vents.

Pull over, shut engine off, restart engine, system appears to re-boot, and it works correctly again.

Once I even heard what I thought was an oscilalting solenoid somewhere under the dash on the driver's side, right above where my knees are below the dash.

Has happened 2-3 times now. I guess I'll report that when they re-finish my wheels and see what may be happening there.

Anyone else had a tempramental auto-climate control?????

Nope... but I don't like the Auto Feature on mine. ( Our Acura with dual climate has Auto and it does both heat and cool.)

The Silverado on Auto i have to hit the AC button if i want it to get cold???

And if i crank up the heat and forget about the AC button.. I am running HOT AIR and AC???

Seems silly to me? I would think AUTO woudl be automatic not having to select HOT or Cold just a disired temp and forget it.

Example if i want tit to be 75 in the truck If it is hotter than the AC shoudl kick it down to 75. If it is colder than the heater should kick it up to 75. Seems simple to me?

The A/C is on when you have heat on to take the moisture out of the air. I haven't seen an auto HVAC in a car that doesn't do that. I sent mine to the temp I want and it blows hot or cold air depending on the cabin temperature.