I have had my Deville for two years now. I already have had a problem with the blower fannot turning off, and replaced the Fan Control Module. This winter I have had problems with heat. First I wasn't getting heat in idle, but fine on the highway. I had the whole system flushed, including the rad and heater core. Now I am getting full time heat, but it isn't blowing very hard. I put a used FCM on when I replaced it, so my question is, does it control speed too? I notice that when I turn it on low speed, it goes lower, but when fan is on high its blowing harder, but not by as much as I would think. One other thing, when I first put the fan on when the car is cold, it whistles for aboutfiveseconds then goes away. Anyone have any idea what the issue is? I do get all vents to work, so I don't believe its a problem with venting. I just know that I can have the fan blowing high all the way home on a forty minute drive, and today it couldn't clear my windows of snow/ice. I had to stop and scrape twice so I could see out the windshield.

 

Check out the blower motor, could be headin south