Why do you think Eddie was lying about his plan to go back to studying air conditioning?

Eddie is bored out of his mind studying air conditioning at Fresno City College. It seemed like a good idea at the time—a chance to learn some vocational skills that might have given him the opportunity to get a career and move out of the neighborhood. But for Eddie, college is just like high school: the teachers are uninspiring, and the other students just don't seem to care.
So it's not much of a surprise when Eddie drops out of college altogether. At the same time, he doesn't want anyone to think he's some kind of loser or a failure in life, so he keeps up the pretense that he's still studying. He manages to appear so enthusiastic to Mr. Stiles about his future career in air conditioning that he almost convinces himself that he'll one day end up tightening bolts on roof-top air conditioning units. But it's all just a big con. (An air-con, you might say.)