Well it's not doing it now. It's running but there's no excess frost/smoke and no smell whatsoever. DH is not concerned-he can't smell it (I can't either, anymore) and says because the house is so hot that's why it's running so long and why there was so much frost. This thing is old enough that it worries me that it's past its prime. DH is in a complete state of denial so I guess I will let it die, let all the food rot, and then we'll deal with it.