2004 focus 80,000 miles/6 weeks ago, using ac with blower on high, blower gradually shut off and car produced bad smell. Drove home with ac off, blower off, had car checked and nothing found. Now it's heating/defrosting season in Wis., if blower is on high, at times it slowly shuts off, have been using only 2 or 3rd setting, never 4(hi). Now it's shutting off at times from those settings. If I wait a few minutes, I can turn it on and blower works for a while, makes an odd whirring sound for a bit, and may or may not continue to work. Intermitent problem happening more often lately. Is this the blower motor going bad? Any suggestions? Way too cold here to be without reliable heat in car.