--- title: "Microwave Vent Fan Not Pulling Steam: Causes and Fixes" description: "A microwave vent fan not working lets steam and smoke from the pans roll up past the door, runs but moves little air, will not turn off, or switches on by…" url: "https://microwaverepair.center/problems/microwave-vent-fan-not-working/" --- # Microwave Vent Fan Not Pulling Steam A microwave vent fan not working lets steam and smoke from the pans roll up past the door, runs but moves little air, will not turn off, or switches on by itself, and it belongs only to a microwave mounted above the cooking surface. ## What it usually means. A microwave hood combination has two fans: a small cooling fan that runs whenever the microwave heats, and a larger vent fan that draws air from under the unit through grease filters and pushes it out through a duct to the outside or back into the kitchen through a charcoal filter. The vent fan has its own keys, speeds and often an automatic mode: a heat sensor underneath switches it on when a pan below gets hot and keeps it running until the heat drops, to protect the microwave's electronics. That mode surprises owners, and a fan that will not shut off while the burners are hot is usually doing its job. A fan that runs but does not draw has clogged grease filters, a charcoal filter past its life, a damper stuck shut in the duct, or a unit set up to blow one way while the duct runs another. A fan that does not run at all points to the motor, a cutout on it, the switch or relay, or the board. The fan and its wiring sit inside the outer case, next to the high-voltage section. The 6 causes, cheapest first Answer these first 01 Does the fan not run at all, run weakly, or refuse to turn off? 02 Does it switch on by itself when the burners run on high? 03 Are the grease filters under the microwave packed with grease? 04 Does the air leave the home through an outside cap, or come back into the kitchen through the grille above the door? 05 Does the microwave itself still heat normally? ## Check these before you book. Microwave vent fan not working: 5 checks, and none of them costs anything. 01 Slide out the grease filters, soak them in hot water with a degreasing soap, and let them dry before they go back. 02 Turn the burners off and let the area cool; if the fan then stops, the heat sensor was running it on purpose. 03 Try every fan speed key, and check whether air reaches the outside cap or the grille above the door. ### Also worth checking - On a unit that recirculates, check how old the charcoal filter is; many makers suggest a new one every six months to a year. - Tell us what the fan does and does not do, and send the model number from the label inside the door frame. ### How soon does it need a visit? Not urgent in itself, but cook with care until it works: without the fan, heat and grease from the pans rise into the bottom of the microwave, and packed filters over a flame can catch. Keep the burners moderate and a lid close at hand until it is repaired. ## The causes, cheapest first. 6 things microwave vent fan not pulling steam turns out to be, from automatic heat sensing doing its job to a fan relay or key on the board. [The cost guide](https://microwaverepair.center/cost/) 1. 01 no repair ### Automatic heat sensing doing its job The sensor under the unit starts the fan when the pans below get hot and holds it on until they cool, whatever the keys say. Turning the burners down and waiting is the test. No repair: check it yourself [On a microwave hood combination](https://microwaverepair.center/types/over-the-range-microwave-repair/) 2. 02 no repair ### Grease filters packed shut Mesh filters thick with grease pass little air, and the fan roars while steam still rises past it. They slide out by hand and soak clean in hot water with a degreasing soap. No repair: check it yourself [On a microwave hood combination](https://microwaverepair.center/types/over-the-range-microwave-repair/) 3. 03 lowest ### A spent charcoal filter On a unit that recirculates, the charcoal filter behind the top grille clogs and stops holding odors. It cannot be washed and is replaced by model number. [Fixed by microwave vent fan and filter repair](https://microwaverepair.center/services/microwave-vent-fan-and-filter-repair/) [On a microwave hood combination](https://microwaverepair.center/types/over-the-range-microwave-repair/) 4. 04 low to moderate ### A damper stuck or a duct blocked The flap in the duct or at the outside cap can stick shut with grease, paint or a bird's nest, and a duct crushed in the cabinet above chokes the flow. [Fixed by microwave vent fan and filter repair](https://microwaverepair.center/services/microwave-vent-fan-and-filter-repair/) [On a microwave hood combination](https://microwaverepair.center/types/over-the-range-microwave-repair/) 5. 05 moderate ### Fan motor or its cutout failed A motor that hums without turning, turns slowly, or stops after a few minutes has worn bearings or an open cutout. It is replaced with the unit on the wall or taken down, depending on the model. [Fixed by microwave vent fan and filter repair](https://microwaverepair.center/services/microwave-vent-fan-and-filter-repair/) [On a microwave hood combination](https://microwaverepair.center/types/over-the-range-microwave-repair/) 6. 06 moderate ### A fan relay or key on the board When one speed works and another does not, or the fan will not start from its key but runs on automatic, the relay or the keypad is the suspect. [Fixed by microwave control board and touchpad repair](https://microwaverepair.center/services/microwave-control-board-and-touchpad-repair/) [On a microwave hood combination](https://microwaverepair.center/types/over-the-range-microwave-repair/) ## What else it could be. Most often confused with microwave light out inside or underneath, then loud hum, buzz or grinding from a microwave. [All problems](https://microwaverepair.center/problems/) Codes that come with it - [`F3T3` JennAir · Sensors and temperature](https://microwaverepair.center/error-codes/jennair-f3t3/) - [`F7E9` JennAir · Fans and ventilation](https://microwaverepair.center/error-codes/jennair-f7e9/) - [`F2H1` JennAir · Fans and ventilation](https://microwaverepair.center/error-codes/jennair-f2h1/) - [`F8E5` JennAir · Sensors and temperature](https://microwaverepair.center/error-codes/jennair-f8e5/) - [`Change the Charcoal Filter` KitchenAid · Fans and ventilation](https://microwaverepair.center/error-codes/kitchenaid-change-charcoal-filter/) - [`F2H1` KitchenAid · Fans and ventilation](https://microwaverepair.center/error-codes/kitchenaid-f2h1/) [3 more codes, by make](https://microwaverepair.center/error-codes/) Also related - [**What a Microwave Error Code Is Telling You** 7 causes](https://microwaverepair.center/problems/microwave-error-code/) ### Microwave Light Out Inside or Underneath 6 causes ### Loud Hum, Buzz or Grinding From a Microwave 6 causes Stop using it ### Burning Smell From a Microwave 6 causes ## The makes it happens on. 18 makes on this site; microwave vent fan not pulling steam can show up on any of them. Each mark opens that make's own page. [All 18 brands](https://microwaverepair.center/brands/) ## Microwave Vent Fan Not Pulling Steam, where we come out. 9 metros, each with its own page. 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A heat sensor under it turns the fan on when the pans below get hot, to protect the microwave. It stops once the area cools, and the keys cannot override it while the heat is high. ### How often should the grease filters be cleaned? About once a month with everyday cooking, more often with frying. Many metal filters can also go in a dishwasher if the manual allows. ### Can a microwave mounted over the burners vent outside? Many can, through the top or the back, set up at installation. The duct and the outside cap belong to the house; the fan, its motor and its damper inside the unit are ours to repair. ### The fan is loud but hardly moves any steam. Why? Usually a clogged filter, a damper that no longer opens, or a crushed section of duct. The motor spins, but the air has nowhere to go. --- **[Read on the site: Microwave Vent Fan Not Pulling Steam: Causes and Fixes](https://microwaverepair.center/problems/microwave-vent-fan-not-working/)** **[Book a visit with MicrowaveRepair.center](https://microwaverepair.center/schedule/)**