Regular maintenance is important for roof package units. They are more prone to weather damage, and so should be checked regularly for problems. A technician should also check to ensure the unit is not damaging your roof.Additionally, if you notice the following signs, make sure to contact the experts at Russell’s Heating and Air Conditioning immediately.Not enough heated or cooled air. Dust build-up. Thermostat not working. Bad smells when the system is on. Too little air coming out of the vents.