Musty or spoiled grain odor.
Cause: Heat or moisture accumulation in one spot.
Solution: Run the fan to cool hot spots, if damage is too severe remove grain.
Hard layer below grain surface.
Cause: High moisture or spoiled and caked grain mass.
Solution: Run aeration or drying fan. If caked or compacted mass blocks airflow remove and resume cool and dry airflow.
Warm grain below surface.
Cause: High moisture.
Solution: Run aeration fans regardless of external weather conditions until the exhaust air temperature measures as the desired grain temperature.
Grain is wet, slimy, sticking or frozen together.
Cause: Early moisture migration—noticeable in the first two weeks grain is in the bin.
Solution: Run aeration fans to cool grain until exhaust temperatures equal outside air temperatures or your desired grain temperature.
Hard, caked crust blocking airflow.
Cause: Severe moisture migration and condensation in the top layer.
Solution: Removed spoiled grain and run fans to cool remaining grain. Take samples to find conditions of grain under the crust.
Roof condensation dripping onto grain surface.
Cause: Warm grain in cold weather, severe convection circulation and moisture migration.
Solution: Aerate until exhaust temperature equals the outdoor air temperature at the beginning of the cycle.
Wet/spoiled spots outside of center of grain.
Cause: Condensation drips from bolt ends or under roof fixture that funnels condensation flow or roof leak.
Solution: Check for hot spots, check roof under surface at night and check for caulking around roof inlets and joints.
Wet/spoiled spot under fill cap.
Cause: Leaking roof cap or condensed water from gravity spout.
Solution: Check bin cap seal, block or disconnect gravity spout so air cannot flow up tube. Short term: Hang bucket under spout inlet and check for water.
No air flow with while fans are running.
Cause: Caked or moldy grain mass blocking air or moldy grain layer above aeration duct or perforated floor on suction system.
Solution: Find spoiled grain to determine location and scope, unload bin and market good grain.
White dust when stirred.
Cause: Mold on top layer.
Solution: Evaluate grain, determine extent of damage and decide if grain will continue to deteriorate.
Cooling takes longer than normal.
Cause: Fines in grain reducing airflow or two to four times airflow resistance when compared to clean grain.
Solution: Run the fans longer, until grain and exhaust temperatures show desired temperature.
Exhaust air temperature in center of bin surface warmer than off-center.
Cause: Fines accumulate in the center and resist airflow, making the airflow in the center less than surrounding areas, therefore hotter.
Solution: Run the fan long enough to cool the center exhaust, draw down bin center to remove find and decrease depth for easier air flow in core.
Source: Perdue University