--- title: "Bosch under-cabinet fan key flashing slowly: the heat sensor has the blower" description: "What Fan key backlight flashes slowly means on Bosch under-cabinet fan key flashing slowly: the heat sensor has the blowers, what to check before booking, and…" url: "https://rangehooderepair.center/error-codes/bosch-fan-key-flashing/" --- # Bosch under-cabinet fan key flashing slowly: the heat sensor has the blower The thermostat reacts to excessive heat above the cooking surface. ## What Fan key backlight flashes slowly actually means. The thermostat reacts to excessive heat above the cooking surface. With the blower off it starts it at high; with the blower on low it steps up to high. While it is in charge, the fan key flashes slowly, the speed cannot be changed, and the control panel cannot turn the hood off, only the main power switch can. Bosch range hood display · also shown as Heat sensor active What to do when Fan key backlight flashes slowly shows on the range hood ### Kind of code Heat and grease sensors A sensor inside the canopy has stopped telling the control a believable story: the heat sensor that starts the fan when the air above the burners gets hot, or on some hoods a sensor that reads grease or steam to set the speed. One that reads hot all the time keeps the blower running with the burners long cold; one that reads nothing leaves the automatic mode doing nothing. The sensor, its wiring and the canopy around it are checked at the visit. ### Usually leads to Range hood heat sensor repair Testing the sensor that starts the fan by itself when the burners get hot, so the hood starts when it should and stops when the heat is gone. ### Shows up as Reading a Range Hood Error Code or Blinking Light A range hood error code may appear as letters and numbers on a display, a light that blinks in a pattern, a filter reminder that will not clear, or a beep with the fan refusing to start. ### Make Bosch Bosch range hoods and downdraft vents get a home visit in which the touch controls and the fan's timed shut-off are checked before anything is opened. ### Source Bosch Undercabinet Hood User Manual (DUH and DUHP models) Bosch under-cabinet hoods DUH30253UC, DUH56353UC, DUH80553UC, DUH86553UC and pull-out models DUHP0853UC, DUHP6853UC. ## Before you book, in this order. Each step comes from Bosch's own guidance for Fan key backlight flashes slowly on its range hoods. Follow it to the end: the last card says whether this is a visit. 01 Leave the blower running and lower the heat under the pans. 02 Wait for the temperature to fall; the blower returns to its earlier setting on its own. 03 If you must stop the blower, use the hood's main power switch as the manual describes. 04 Book a visit if the heat sensor triggers with little heat below or never lets go. ### Still there? It usually turns into [range hood heat sensor repair](https://rangehooderepair.center/services/range-hood-heat-sensor-repair/). Book with the code and the model number. ### What not to do This is not the automatic mode you switch on with its key, which adjusts speed to cooking heat and turns the fan off afterward. A key flashing only at switch-off is the filter reminder, not the sensor. ## What you may notice with it. The range hood problems Fan key backlight flashes slowly tends to arrive with. Answer these at the range hood before anyone is booked. [All problems](https://rangehooderepair.center/problems/) Before you call ### [Reading a Range Hood Error Code or Blinking Light](https://rangehooderepair.center/problems/range-hood-error-code/) [All 7 causes, cheapest first](https://rangehooderepair.center/problems/range-hood-error-code/) It also comes with - [**Range Hood Fan Won't Turn Off**](https://rangehooderepair.center/problems/range-hood-fan-wont-turn-off/) - [**Range Hood Fan Stuck on One Speed**](https://rangehooderepair.center/problems/range-hood-stuck-on-one-speed/) Problem ### Reading a Range Hood Error Code or Blinking Light 7 causes, cheapest first Where Fan key backlight flashes slowly usually leads ## Range hood heat sensor repair. **Heat sensor or thermostat disc and its lead · low.** Book a visit [What the job involves](https://rangehooderepair.center/services/range-hood-heat-sensor-repair/) ## Bosch range hoods. Bosch range hoods and downdraft vents get a home visit in which the touch controls and the fan's timed shut-off are checked before anything is opened. [Bosch range hood repair](https://rangehooderepair.center/brands/bosch/) More Bosch codes [clean grease filter](https://rangehooderepair.center/error-codes/bosch-clean-grease-filter/) [replace charcoal filter](https://rangehooderepair.center/error-codes/bosch-replace-charcoal-filter/) [Auto](https://rangehooderepair.center/error-codes/bosch-auto/) [End](https://rangehooderepair.center/error-codes/bosch-end/) [Snd](https://rangehooderepair.center/error-codes/bosch-snd/) [Able](https://rangehooderepair.center/error-codes/bosch-able/) [GREASE FILTER lit](https://rangehooderepair.center/error-codes/bosch-grease-filter-key-lit/) [CHARCOAL FILTER lit](https://rangehooderepair.center/error-codes/bosch-charcoal-filter-key-lit/) [CONNECT and 2 flashing](https://rangehooderepair.center/error-codes/bosch-connect-2-flashing/) [Two short beeps](https://rangehooderepair.center/error-codes/bosch-two-short-beeps/) [Filter key flashes slowly at switch-off](https://rangehooderepair.center/error-codes/bosch-filter-key-flashing/) Heat and grease sensors on other makes [Elica CArE](https://rangehooderepair.center/error-codes/elica-care/) [GE Profile Indoor Air Quality (IAQ) LED changing color](https://rangehooderepair.center/error-codes/ge-profile-iaq-led/) [Monogram Indoor Air Quality (IAQ) LED](https://rangehooderepair.center/error-codes/monogram-iaq-led/) [Sirius Motor stops during high-heat cooking](https://rangehooderepair.center/error-codes/sirius-thermal-overload/) [Thermador AUTO blinks 3 times](https://rangehooderepair.center/error-codes/thermador-downdraft-auto-blinks/) Bosch builds this ### Wall-mount range hood The chimney hood fixed to a bare stretch of wall above the burners, its canopy catching the rising smoke while a telescoping cover hides the duct that climbs to the ceiling. Bosch builds this ### Under-cabinet range hood The slim hood screwed to the bottom of the wall cabinet over the burners, venting up through that cabinet or back through the wall, or cleaning the air and returning it to the room. Bosch builds this ### Island range hood The hood that hangs from the ceiling over burners set into a kitchen island, open on all four sides, with its duct and wiring hidden inside a chimney that drops from above. ## In Bosch's own words > When the heat sensor is activated, the fan key backlight [Bosch Undercabinet Hood User Manual (DUH and DUHP models)](https://media3.bsh-group.com/Documents/8001296852_D.pdf) [Bosch Undercabinet Hood User Manual (DUH and DUHP models)](https://media3.bsh-group.com/Documents/8001296852_D.pdf) [Bosch Undercabinet Hood User Manual (DUH and DUHP models)](https://media3.bsh-group.com/Documents/8001296852_D.pdf) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Bosch under-cabinet hoods DUH30253UC, DUH56353UC, DUH80553UC, DUH86553UC and pull-out models DUHP0853UC, DUHP6853UC. ## Bosch Fan key backlight flashes slowly range hood repair, where we come out. The same visit in every metro below: the code, the model number, and a diagnosis before any part is ordered. 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Leave the blower running and lower the heat under the pans. If it comes back, it needs a visit. ### Why won't my Bosch under-cabinet hood turn off from its buttons? If the fan key is flashing slowly, the heat sensor started the blower and the panel cannot override it. It shuts down once the heat drops, or you can use the main power switch. ### What sets off the heat sensor on a Bosch under-cabinet hood? Excessive heat rising from the cooking surface, such as several high burners or a wide pan searing directly below. ### Is a Bosch hood that runs on high by itself a sign of trouble? Not when the fan key is flashing and the burners are hot; that is the sensor at work. With a cold cooking surface, it points to a sensor or control that needs testing. --- **[Read on the site: Bosch under-cabinet fan key flashing slowly: the heat sensor has the blower](https://rangehooderepair.center/error-codes/bosch-fan-key-flashing/)** **[Book a visit with RangeHoodeRepair.center](https://rangehooderepair.center/schedule/)**