Hi. I just bought a wall unit and turned it to “low fan” setting. Within I think a few seconds after it started, I could hear it slowing down, which it continued to do until it came to stop, which only took like 2 minutes. I am charging my cell phone so I can video record it when I turn it to “high fan” setting. I turned to “high fan” setting just for a second to see if it would come on and it did. Can you tell me what types of things could be the problem here? Thank you.