I just replaced the blower motor in my 91 DeVille sedan with one from a junk yard. The guy said that the one that he gave me from a early 90's Eldorado would work. I have read somewhere that you do not want to mix models. Now my heat will not go above 78 without going back down to 75 and showing a C instead of the climate and gas info. Has this ever happened to you any of you guys? Is it because i got the motor from a Eldorado?