Why does your AC smell musty?
A musty odor is a reason to investigate moisture and the HVAC system. Odor alone does not establish that there is mold, where it is, or which work is needed.
Describe when you notice it
Tell the office whether the odor begins when the AC starts, stays after it stops, affects one room, or comes with visible water. Note recent filter changes or water damage. Do not open equipment or apply a chemical spray inside it.
Ask for the source of the problem
A technician can inspect accessible HVAC components and drainage. A wet filter, drain problem, or moisture elsewhere in the building may need different work. If someone reports mold, ask what they observed and what supports the finding.
EPA explains that routine duct cleaning has not been shown to prevent health problems. Its duct-cleaning guidance describes when further investigation may be warranted. Suspected mold contamination needs appropriate professional advice; do not run contaminated equipment merely to mask an odor.
Do not use an accessory to hide a fault
Fragrances, sprays, or an air-treatment accessory do not repair a leak or remove a moisture source. Ask how a proposed repair addresses the finding, what it includes, and what remains outside the HVAC contractor’s scope.
Request a visit
A repair diagnosis has a visit charge. Read what a repair visit costs for the first-hour charge, additional time, parts, after-hours rates, and travel charges. The technician explains repair options and costs before you approve repair work.
For urgent gas or safety concerns, follow emergency guidance rather than waiting for an HVAC request to be answered. If you smell gas, leave the area and call 911 from a safe place outside. Do not operate switches or try to find the leak. See PG&E’s gas-safety instructions.
