A truck is only ever as reliable as the parts that comprise it. Now, while an internal component like the a/c heater control in your Chevrolet K1500 Suburban does not directly contribute to fantastic performance nor does it give extra boosts of power, it's still one very important component to keep tabs on-lest you get left out in the cold-literally. The difficulty with internal components like the a/c heater control is that they're neither visible nor is it a simple task to notice any defects with it. There are some things to look out for-you just really need to be vigilant.
The first and most visible sign of wear or failure of your a/c heater control is the most obvious: the air conditioning does not heat or cool properly. By "properly", we usually mean that it doesn't work at all. Now, this indicator is not an exclusive symptom of a failure with the heater control-other culprits could be a lack of Freon, a failure of the a/c clutch, or a busted blower. It does give you an excellent indicator and reminder to include the a/c heater control in the inspection as you seek out the specific component at fault.
You'll know that it is, in fact, the heater control at fault when the most vulnerable components of the control-like the blend doors, the motor, or the cores-are inactive or show visible signs of damage. These parts can survive on quick fix replacements-like replacing or jury-rigging the hinges-but at this stage, it's safer to consider replacement.
Another sign to look out for that more specifically tags the a/c heater control as being at fault is when the above symptom is accompanied by inconsistent output from the air conditioning unit. The two symptoms together isolate the problem by eliminating other parts that will manifest only one or the other. Again, the erratic distribution of air from the unit is due to damage with the components that make up the heater control.
One quick fix, is to review the fault codes that are stored in the heater control-as reference when taking it in for repairs-or, if you're up to the task, upgrading the software of the control if it is computerized. Analog heater controls are somewhat easier to quick fix because parts are available in used car shops or discount parts bins.