Please Help! Blanket Problems!!?

I live in MN and its cold, like 5-17 degrees each day sometimes warmer, i bought my mare a 1200denier tough 1 blanket and she seems like she might be to hot at times, i just put it on her 2days ago, she has her winter coat and it s healty weight, the bad thing is she seems alittle sweaty on her chest! Should i bring in the stall for the night and take of her blanket, so she can get used to the colder temps again and then only put the blanket on during windy, snowy, blizzardy conditions? Because im just concered its to much blanket...THANKS ! Any advice would be appreciated:)