Two trucks with different HVAC responses

[canuck57]

I purchased a 2015 Sierra SLT 2500 hd (diesel) in August 2014 and picked up a Sierra 1500 sle sierra work truck in April 2015. Here's the issue when I use the hands free in the 2500hd the radio goes silent and the HVAC fan speed stays at whatever speed it was in when I started to use it......now my 1500 reacts differently, when I engage the hands free, the radio goes quiet BUT the HVAC goes into low speed until I am done with the call. Are these two different systems? I would think the 2500hd would have this low speed option built-in as it is helpful and makes the call clearer (less background cabin noise)
Anyone know which truck is functioning correctly?

 

[2013Denial]

My 2013 2500 HD slows the fan when on a call. It must be some thing that can be customized in the settings or something. Not sure where to tell you to look but wanted you to know that the 2500HD's can do it also.

Maybe it's a trim level option?