Restaurant Exhaust Fan Problems: Weak Suction, Grease Leaks and Belt Wear

The exhaust fan is the engine of the kitchen exhaust system. It usually sits on the roof or in a plant room, so problems go unnoticed until the kitchen fills with smoke. These are the problems we see most often and what usually causes them. For noise in particular, see why a kitchen exhaust fan is noisy.

Weak suction

• Grease on the fan blades changes their shape and weight, so they move less air
• Clogged filters or a greasy duct restrict the airflow before it reaches the fan
• A slipping or worn belt makes a belt-driven fan turn slower than it should

Grease leaking on the roof

Grease that collects in the fan housing eventually drips out around the fan base or outlet. It stains the roof, can damage roofing materials, and is a fire risk. A grease container or drain on the fan helps, but the real fix is cleaning the fan and the duct before the grease builds up.

Vibration and wobble

Uneven grease on the blades throws the fan out of balance. The vibration wears the bearings and mounts and makes noise. Cleaning the blades evenly often stops it; worn bearings need a mechanic.

Belt wear

Belts on belt-driven fans stretch and crack with heat and grease. A squeal at start-up or a belt that looks glazed or frayed needs attention from a fan technician. Grease on the belt makes it slip, which is another reason to keep the fan clean.

What cleaning fixes and what it does not

Cleaning removes grease from the blades, housing and motor compartment, which restores balance and airflow in many cases. It does not replace worn bearings, belts or motors; if we find those during cleaning, we note them in the report. See our kitchen exhaust fan cleaning service.

Frequently asked questions