A childhood belief about around the house

When I was about 5 years old (I think), our air conditioner had a loud rattle
when it ran. My family told me that it had a jar in it, I suppose meaning that it was
jolting in the window. The more they tried to tell me it was o.k, the less o.k. it was
with me, because all I could think of was, that with all that rattling, that jar is going to
break and the glass is going to come out and fly all over and hurt anyone near
by. Finally, Dad fixed the "jar in the air conditioner". Days or weeks later, I was playing in the
garage, I saw an old peanut butter jar with some dirty water in it. Knowing of course
that dirty water dripped out of the air conditioner, I figured it was the "jar" that was
in the air conditioner. All in one piece, no less.