Instruct: Classify a given review into positive or negative sentiment.
Query: two shipments were defective.

the first unit arrived and the heat indicator lamps did not come on.on first use of the replacement unit, after about ten minutes the fan stopped. the heat was set to fairly high and did not go off. some smoke. i assume there is a safety thermostat that would have kicked in, but without the fan the coils glowed for a while.it may be a bad batch - but there seems to be no quality control at all.