I absolutely hate the mandated A/C useage when in either of the "defrost" vent mode positions are selected. Often it isn't really necessary, and just wastes fuel and adds needless wear and tear on the A/C system.
But GM figured that most drivers are morons, and can't figure out when the dehumidification benefit of A/C use in defrost mode is needed, and isn't.
And they're right...
But I can figure it out, and this feature bugs the hell out of me.
So I figured out how to disable it from mandatory to optional with the use of the "A/C" button only.
As most of you know, the temperature and vent "mode" control operate with mechanical cables, but there is some electronic manipulation going on as well, mainly with A/C, rear defroster and recirculation operation.
But I figured out that one of the brush contacts on the mode dial that sweeps across contacts on the front of the circuit board seems to primarily control A/C engagement, and just pried the brushes off of the back of the mode knob to prevent the circuit board from being able to determine mode knob position.
Now doing this mod likely disables any recirculation and possibly rear defroster automatic features as well, but that's fine with me, as I'm also able to figure out when those features are needed on my own too, and prefer full manual control over them as well.
Naturally, if you still want dehumidification of the inside of the windshield in "defrost" position, you just use the manual A/C button to get it.
All the features, A/C, recirc, and rear defrost still work after this mod, by pressing the buttons for them.
And this isn't going to go into details about how to remove the climate control panel, or how to disassemble the panel to do this mod. There are plenty of how-to's and videos out there for that.
Although I will say not to worry when you remove the 6 screws that hold the control knobs onto the circuit board, and it appears they won't re-align correctly.
Just take your time and make sure the square and round pegs go back into their respective holes on the board, and everything will fall back into place then...
I used needle nose pliers to pry the brushes off of the knob, although small knives and flat blade screwdrivers would probably work too.
Just make sure you don't break off the indexing pins on the knob, and also be sure that the pieces that you break or cut off don't get dropped into and left inside the housing, where they might get caught in the plastic gears and jamb knob rotation.
This pic shows which brush needs to be removed.
Also, the knob is shown in the fully left (counter-clockwise) "vent" position, for reference.
But GM figured that most drivers are morons, and can't figure out when the dehumidification benefit of A/C use in defrost mode is needed, and isn't.
And they're right...
But I can figure it out, and this feature bugs the hell out of me.
So I figured out how to disable it from mandatory to optional with the use of the "A/C" button only.
As most of you know, the temperature and vent "mode" control operate with mechanical cables, but there is some electronic manipulation going on as well, mainly with A/C, rear defroster and recirculation operation.
But I figured out that one of the brush contacts on the mode dial that sweeps across contacts on the front of the circuit board seems to primarily control A/C engagement, and just pried the brushes off of the back of the mode knob to prevent the circuit board from being able to determine mode knob position.
Now doing this mod likely disables any recirculation and possibly rear defroster automatic features as well, but that's fine with me, as I'm also able to figure out when those features are needed on my own too, and prefer full manual control over them as well.
Naturally, if you still want dehumidification of the inside of the windshield in "defrost" position, you just use the manual A/C button to get it.
All the features, A/C, recirc, and rear defrost still work after this mod, by pressing the buttons for them.
And this isn't going to go into details about how to remove the climate control panel, or how to disassemble the panel to do this mod. There are plenty of how-to's and videos out there for that.
Although I will say not to worry when you remove the 6 screws that hold the control knobs onto the circuit board, and it appears they won't re-align correctly.
Just take your time and make sure the square and round pegs go back into their respective holes on the board, and everything will fall back into place then...
I used needle nose pliers to pry the brushes off of the knob, although small knives and flat blade screwdrivers would probably work too.
Just make sure you don't break off the indexing pins on the knob, and also be sure that the pieces that you break or cut off don't get dropped into and left inside the housing, where they might get caught in the plastic gears and jamb knob rotation.
This pic shows which brush needs to be removed.
Also, the knob is shown in the fully left (counter-clockwise) "vent" position, for reference.
Attachments
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20190211_193932.jpg
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