Chimney-style range hood with a glass canopy over a cooktop
8 components covered

Field manual · Range Hood

Broan-NuTone under-cabinet range hoods (40000 / 41000 / 42000 / BCSQ Glacier): field service manual

Covers: Broan and NuTone 30-42 in under-cabinet hoods: 40000 series (3-1/4 x 10 in ducted), 41000 series (non-ducted, charcoal), 42000 series (7 in round ducted) and convertible BCSQ/Glacier types with LED lighting. Many are discontinued but still installed everywhere.

Cross-checkedBrands: Broan, NuTone8 components

The most common hood in US rentals and tract homes. Older series use a simple rocker or slide switch, a small shaded-pole or PSC motor and an incandescent or LED lamp; newer Glacier/BCSQ units add a multi-speed blower, push-button control and LED modules. The first job on any call is to identify whether the unit is ducted, non-ducted or convertible and which duct it was built for.

Safety first

  • Breaker off before removing filters near the fan or opening any cover; tape the breaker and use a non-contact tester.
  • Live voltage tests are caution work: insulated probes, one hand, no contact with the metal hood body.
  • Discharge any capacitor before testing.
  • Wear gloves; hood edges are sharp.
  • If a gas range is below, do not move or adjust the range gas connection; refer gas work to a licensed contractor.

How it works

Ducted versions (40000, 42000, BCSQ ducted) pull air through the grease filter into a blower and push it through a damper into the duct. The 40000 series is 3-1/4 x 10 in rectangular only; the 42000 series is 7 in round only; convertible BCSQ units take 7 in round or 3-1/4 x 10 in.

Non-ducted versions (41000 series and convertible units with a kit) pass air through a grease filter and a charcoal filter and blow it back into the kitchen. They do not remove heat or moisture; Broan says to replace the charcoal filter about every 6 months, sooner with greasy cooking.

Controls on older series are simple switches feeding a 2-speed motor and a lamp; newer models use a control board with push buttons. All run on a 120 V branch circuit, hard-wired in a knock-out box or with a plug-in cord kit where allowed.

Airflow: entry 40000/42000 units are rated roughly 160-190 CFM at about 6 sones (check the label); Glacier BCSQ130 is listed at 375 max CFM and 1.5 sones normal. Airflow drops fast with a dirty filter, a stuck damper or a duct smaller than the outlet.

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Chimney-style range hood with a glass canopy over a cooktop by Bilguun Gantumur, Pexels License

Diagnostic guides for this appliance

Guide · Range Hood

Range hood fan runs only on high, runs slow, or a speed is missing

On simple switch hoods, a missing speed is usually the switch or a failed winding tap; on board-controlled hoods it can be a relay on the control. A fan that is slow on every speed points to grease-dragged bearings, a weak run capacitor on PSC motors, or airflow restriction. Check mechanical drag and airflow before electrical parts.

8 steps ~45 minmoderate
Guide · Range Hood

Cold air, odors or insects coming in through the range hood when it's off

Two dampers should block the duct when the fan is off: one at the hood and one in the wall or roof cap. Grease, bends, missing springs or screws in the path keep them open. Long duct runs and a house under negative pressure make it worse. Fix the dampers first; make-up air questions go to code and an HVAC or licensed contractor.

7 steps ~60 minmoderate
Install · Range Hood

Range hood ducting: duct size, route, termination and makeup air

Hood performance depends more on the duct than the blower. Use the duct size the hood requires (never smaller), smooth metal duct, as few elbows as possible, and a proper wall or roof cap with a damper. Larger hoods can trigger a makeup-air requirement under local code (commonly when the hood can exhaust more than 400 CFM in homes with certain fuel-burning appliances).

6 steps ~240 minadvanced

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Range hoods (under-cabinet, wall chimney, island): ducted vs recirculating field manual

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Broan-NuTone under-cabinet range hoods (40000 / 41000 / 42000 / BCSQ Glacier): field service manual · OnCall Tech