It is almost the time of year when I disconnect the plug from the A/C clutch. Here is why:
Here in the Southwest there are days when the ambient temperature is above 65 degrees F, which is the temperature that the outside air temperature switch is set at (located on a bracket in front of the radiator on my car). This switch is in series with the compressor clutch. Even though the control is calling for heat, the A/C compressor can come on, hurting fuel economy. The climate control mixes hot air with cold air to control the temperature.
The only thing that this can hurt is the defogger can't work like it was designed, but in a dry climate such as I am in, it is rarely used anyway.
To be honest, I wish it had the more normal A/C and heat controls rather than climate control.