have (one's) heart (dead) set against (something)
To be vehemently opposed to something or some action. After he moved to France, he had his heart dead set against ever returning to London. I'm sorry, I have my heart set against that color for the living room.
have one's heart (dead) set against something
Fig. to be totally against something; to be opposed to something. Jane has her heart dead set against going to Australia. John has his heart set against going to college.