GMC Yukon Heater question

I drive a 1998 GMC Yukon. The front heater stopped blowing out air. (You can feel the warmth or cold seeping out, just not blowing) I assumed it was just the blower motor but, my stereo started acting up as well. The stereo seems to work but, the speakers cut in and out, sometimes I can go an entire car ride without them coming on. The lights on the stereo (it is a stock system) are half out and the lights for the heater dials (right below the stereo) do not work. If I smack the dash a bunch sometimes they'll come on.

Is the heater not blowing the blower motor or can something electrical be going on?