Possibly the old motor was too small. If they replace it with the same
size motor, the new one will burn out too. The nameplate should have
the proper motor size. After they replace it, they should check the
amps to make sure it is working OK. They should also replace the motor
One other possibility is if it is a Goodman or Janotrol or GMC heat
pump. The blowerr relays have a habit of failing in such a way as to
run the strip heat and motor together, hence a burning smell. If that
is tha case, replace the blower relay as well. Sounds like the service
company uses parts replacers instead of techs. If it is not working
right when they are done, they haven't diagnosed the problem properly.
After 5 trips, it appears they cannot.