This Site might show a burned-out wire inside the unit, though a musty odor may well reveal There is certainly mold someplace inside the unit or perhaps the ductwork.If one or more of such signs Appears familiar, it might be time to succeed in out to an HVAC specialist to acquire professional aid.Foul or musty odors when running your HVAC system can suggest a variety of issues. These smells are often attributable to mold or mildew growth, stagnant h2o, directory or accrued particles while in the system. Moreover getting unpleasant, these odors can pose wellbeing pitfalls and compromise indoor air top quality.