u/mosaicmonkey311

Had a mildew smell from HVAC for 2+months. The odor is in the returns and drifts into the house. Worse in evening/overnight. Sometimes its a sour smell as well. Last night was the worst. Both returns smelled mildewy sour and even a sour smell behind the fridge, in the cabinets next to fridge, and along the floor. Could be a different source but it's the same smell that's in the returns. Did all the HVAC checking and cleaning, even have a new furnace and AC but that made the odor stronger. Dozen professionals can not find the cause or source. Plumbers seem to not know much. No one wants to do a smoke test. Any suggestions??