it makes a loud humming or buzzing noise from the fan, not the normal sound. sounds strained.

Diagnosis

The loud humming or buzzing sound in the Cosori Dual Blaze 6.8QT is typically caused by a mechanical imbalance or an obstruction within the high-velocity convection fan system. Unlike the standard "whoosh" of air, a strained buzzing indicates that the fan blade is either making physical contact with the housing or the motor bearings have developed excessive play. Because the Dual Blaze features heating elements both on the top and bottom, the airflow paths are more constricted than in single-element models, making the fan more susceptible to vibration if a foreign object enters the chassis. To confirm the cause, listen closely to the rear intake vents while the unit is running. If the sound is a rhythmic "clicking" or "scraping," it is likely a physical obstruction (like a piece of parchment paper or a food crumb) that has been sucked into the intake. If the sound is a constant, low-frequency vibration or a metallic drone that increases in pitch as the fan ramps up, the issue is almost certainly the motor bearings failing or the fan blade becoming warped due to heat exposure, causing it to clip the plastic shroud.

How to Fix It

Since the fan is located in the lower base of the unit, you must perform a visual and physical inspection of the intake area. Follow these steps precisely:

1. Completely unplug the unit from the wall outlet and allow it to cool for at least 30 minutes to avoid burns from the lower heating element.
2. Carefully tilt the air fryer forward at a 45-degree angle or lay it on its back on a soft towel to expose the bottom intake vents.
3. Using a high-lumen LED flashlight, peer through the ventilation slats at the base. Look for any debris, plastic fragments, or clumps of dust trapped against the fan blades.
4. Use a can of compressed air (duster) to blow short, sharp bursts of air into the intake vents. This often dislodges small particles that are causing the "strained" sound without requiring a full teardown.
5. If you see a visible obstruction, use a pair of long-reach needle-nose pliers or a thin plastic probe to gently remove the debris. Do not use metal screwdrivers that could scratch the heating element or bend the fan blade.
6. Place the unit back on a flat, level surface and restart it on a "Preheat" cycle for 2 minutes to verify if the noise has subsided.

If That Didn't Work

• Check for Surface Resonance: Sometimes the "buzzing" isn't the fan itself, but the unit vibrating against the countertop. Place the air fryer on a thick silicone heat mat or a wooden cutting board. If the noise disappears, the vibration was being amplified by your countertop material.
• Inspect the Basket Seating: Ensure the 6.8QT basket is fully seated and locked. If the basket is slightly skewed, it can disrupt the internal airflow patterns, creating a "buffeting" sound that mimics a strained motor. Remove the basket and run the unit for 10 seconds; if the noise stops, the issue is the air turbulence caused by the basket fit.
• Bearing Lubrication (Advanced): If the unit is out of warranty and you are comfortable with electronics, the fan motor shaft can sometimes be lubricated. This requires opening the chassis to access the motor axle. A single drop of high-temperature synthetic machine oil on the bearing shaft can eliminate a metallic drone, though this is a permanent modification.
• Replacement of the Fan Assembly: If the fan blade is warped or the motor has a dead spot, the entire fan motor assembly must be replaced. Because the Dual Blaze is a sealed unit, this usually requires a professional technician to ensure the heating element alignments remain precise.

Heads Up

• Never use oversized pieces of parchment paper that cover the entire bottom of the basket; the suction can pull the paper into the lower fan, causing immediate motor strain or permanent blade damage.
• Always operate the unit on a hard, flat surface. Placing it on a tablecloth or towel can block the intake vents, forcing the fan to work harder and accelerating bearing wear.
• Avoid using "deep clean" liquids or sprays near the bottom vents, as moisture can seep into the motor bearings and cause corrosion, leading to the humming noise.
• If you smell a "burning plastic" scent accompanying the buzzing noise, unplug the unit immediately and stop use, as this indicates the fan motor is overheating and may pose a fire risk.