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Bathroom exhaust fans › Broan-NuTone › NuTone 763RLN series › S0503B000 motor assembly
Cenipar S0503B000 — what it fits, what it doesn't, and how to swap it
A replacement motor assembly — motor, blower wheel, and mounting plate in one plug-in unit — for the Broan-NuTone S0503B000. This page covers fit, specs, diagnosis, and the full swap, so you can order once and be right.
#ad — Disclosure: The Amazon link on this page is an affiliate link. If you buy through it, we may earn a commission at no extra cost to you. Prices and stock change — the price shown is the last one we recorded, not a live price.
The full assembly as it ships: motor + one-piece blower wheel + mounting plate, with a plug — no wiring to splice.
At a glance
PartS0503B000
Brand (aftermarket)Cenipar
What it isMotor assembly
Motor rating120V · 1.0A · 60Hz
FitsNuTone 763RLN series
ConnectionPlug-in, no splicing
Assembly size≈ 6.5 × 9.5 × 9.25 in
Last price recorded: $30.99 on Amazon, Sep 18, 2026. It may have changed since.
#ad · Amazon ASIN B0GXDJ27BG. Confirm your model number with the 30-second fit check below before ordering.
Quick answer
Buy this if your ceiling unit is a NuTone 763RLN, 763RL, 763RLNB, or 763RLN-R01 and the fan is dead, grinding, or humming without spinning. Don't buy it for a Broan 688, a NuTone 665, or any unit matched to the 89850000 motor — those take different parts, and this one will not fit.
01 The 30-second fit check
Two questions. No tools, no guessing — answer from the label inside your fan (see §2 if you haven't found it yet).
1 · What model number is on the label inside your fan housing?
2 · Does the old motor plug into a receptacle inside the housing (rather than being hard-wired with wire nuts)?
02 Find your model number first
The grille on the ceiling tells you almost nothing. The model number lives inside the housing — this takes two minutes and prevents a wrong order.
Pull the grille straight downThe 763RLN grille is held by spring clips. Grip two opposite edges and pull down gently; squeeze the springs to release it and set the grille aside. The bulb and the fan housing are now exposed.
Look for the label on the inside wall of the housingThe rating/model label is stuck to the inside of the metal housing, usually near the receptacle the motor plugs into. It lists the model (e.g. 763RLN) and the unit's electrical rating: 120VAC, 60Hz, 1.4A total with a 100W bulb.
Cross-check the part number on the old motor plate If the previous repair used the correct part, the assembly you remove will be an S0503B000 or an equivalent marked for the 763RLN series. If the plate is marked for a 665 or 688 instead, someone installed the wrong part before — trust the housing label, not the old part.
Label missing or unreadable?
Measure the housing: a 763RLN housing is 9″ × 9″ × 5¾″ with a 4″ round duct and a grille of about 12″ × 10¾″. If your housing measures differently, stop — identify the unit before ordering anything. A housing measurement plus the grille size is usually enough to identify the model from the manufacturer's spec sheet.
03 Confirmed fits
The S0503B000 assembly is the replacement for the NuTone 763RLN family of fan/light units. These are the models it is made for:
Your unit
Type
Fits?
NuTone 763RLN
Fan / light combo, 50 CFM
Yes
NuTone 763RL
Fan / light combo
Yes
NuTone 763RLNB
Fan / light combo (builder pack variant)
Yes
NuTone 763RLN-R01
Fan / light combo (revision)
Yes
All four are the same basic unit — a 50 CFM, 2.5-sone fan/light with a 9″ × 9″ housing — sold in different channels and revisions. If your label matches one of these, the mounting plate, blower wheel, and plug on this assembly line up with your housing.
04 Does NOT fit — the close-but-wrong parts
Most wrong orders in this category come from two look-alikes. Check yours against this table before you buy.
If you have…
Why this part is wrong
What you actually need
NuTone 665 / 665N series
The 665 uses a different motor — part 89850000 — with a different plate and wheel. The S0503B000 will not mount correctly.
A motor assembly for the 665, listed as replacing 89850000.
Broan 688 / 688-K, 670, 671, 689
Smaller, fan-only units with a different housing and mounting pattern.
The motor for the 688 family — or the 690NT upgrade kit below.
NuTone 693, 695, 696N
Fan/light units, but a different generation and housing from the 763RLN.
The motor specified for those models — not the S0503B000.
Common trap: the NuTone 690NT "upgrade kit"
The 690NT is a popular kit that upgrades older fans to 60 CFM / 3.0 sones — but it is made only for the NuTone 693, 695, and 696N and the Broan 670, 671, 688, and 689. It does not fit the 763RLN, and the S0503B000 on this page doesn't fit those models either. The two product lines look similar in photos and are constantly cross-ordered.
05 Full specs
Two different things get spec'd here: the replacement assembly you're buying, and the 763RLN host unit already in your ceiling.
The S0503B000 assembly (this part)
Part number
S0503B000
Brand
Cenipar (aftermarket replacement for the Broan-NuTone part)
What's included
Motor, one-piece blower wheel, and mounting plate — pre-assembled
Motor rating
120V, 1.0A, 60Hz
Motor type
Shaded-pole, plug-in
Assembly size (approx.)
6.5″ × 9.5″ × 9.25″
Motor speed (RPM)
Not reliably published for this assembly — see the verification note at the bottom of this page rather than trusting a number on a random listing.
What you're looking at: the shaded-pole motor at the heart of the assembly. It's a simple, thermally protected design with no brushes and nothing to service — when it fails, it fails as a unit, which is exactly why the replacement is sold as a complete assembly rather than a bare motor. The two-prong plug is the fit detail that matters: the 763RLN housing has a matching receptacle inside, so the swap needs no wire nuts and no splicing.
The host unit: NuTone 763RLN (manufacturer spec sheet)
Type
Fan / light combination unit
Airflow
50 CFM
Sound
2.5 sones
Rated for baths up to
45 sq ft
Housing
9″ × 9″ × 5¾″
Grille
≈ 12″ × 10¾″
Duct
4″ round
Light
One A19 bulb, 100W max (not included). Fan and light can run separately or together.
Total electrical rating
120VAC, 60Hz, 1.4A (with a 100W bulb fitted)
Blower wheel
One-piece, 4¾″
Motor
Shaded-pole, thermally protected, plug-in (motor and light both plug in)
Listings / placement
Type IC; suitable over a tub or shower when connected to a GFCI-protected branch circuit
Not for
Kitchens; do not use with solid-state speed controls
06 Diagnose before you buy
A dead fan isn't always a dead motor. Run down this table first — two of these five problems are free to fix.
Symptom
Most likely cause
The fix
Hums, but the wheel won't spin
Seized motor bearings, or a wheel jammed by debris. The motor is getting power and trying to turn.
Kill the breaker and try spinning the wheel by hand. Stiff or gritty = the motor is done — this assembly is the fix. Free-spinning = check for an obstruction first.
Grinding, rattling, or much louder than it used to be
Worn bearings or a loose, cracked blower wheel. Noise that has grown over months is wear, not dirt.
Clean the wheel first (§10). If the noise stays, the assembly replaces both worn parts at once.
Light works, fan is dead
The fan side of the unit has failed — almost always the motor. The light working proves power reaches the housing.
This assembly. It's the classic S0503B000 symptom.
Fan and light both dead
No power to the unit: tripped breaker, a failed wall switch, or — over a tub/shower — a tripped GFCI.
Check the breaker panel, the GFCI outlet, and the switch first. Don't order a motor until something in the unit shows signs of life with known-good power.
Fan spins, but the bathroom still steams up
Weak airflow, not a weak motor: a stuck damper, a crushed or disconnected duct, or a wheel caked in dust.
Clean the wheel and check that the damper flap at the duct moves freely and the duct is attached. A new motor won't fix a blocked duct.
The 60-second test
With the grille off and power on, flip the fan switch. A hum means the motor has power but can't turn (motor or jam). Total silence with a working light points the same way. Silence with a dead light too means stop and check power before spending anything.
07 Motor only, this assembly, or a whole new fan?
Three ways to fix a dead 763RLN. The honest tradeoffs:
Bare motor only
Just the motor, reusing your wheel and plate.
Cheapest part on paper
Hard to source for this unit, and the old wheel — often the noisy part — stays
Wheel has to come off the old shaft without cracking
The usual fix
Full assembly — this part
Motor + wheel + plate, pre-assembled, plug-in.
Renews every wear part at once
~10–15 minutes, no ceiling work, no wiring
Your fan stays a 50 CFM / 2.5-sone unit — same performance as new, not better
Replace the whole unit
New fan/light in the ceiling, possibly a different model.
The only route to quieter (under 1 sone) or stronger (80+ CFM) performance
Hours of work: housing, duct, wiring, possible drywall patching
Makes sense if the housing is rusted or you're remodeling anyway
Rule of thumb: if the housing is sound and you were fine with the fan's performance when it worked, the assembly is the right spend. Replace the whole unit only when you want it quieter or stronger — no motor swap can give you that (see §11).
08 Tools you'll need
Stepladder — you'll be working overhead with both hands.
Flat-head and Phillips screwdrivers — the assembly is held by screws through the mounting plate.
Nut driver (¼″) — some plates use hex-head screws instead; covers both cases.
Non-contact voltage tester — to prove the circuit is dead before your hands go in the housing.
Work gloves — cut sheet-metal edges inside the housing are sharp.
Vacuum or old paintbrush — for cleaning the housing while it's open (§10).
Flashlight or headlamp — the breaker will be off; the bathroom light is on the same unit.
No wire strippers, no wire nuts, no electrical tape: this unit is plug-in by design.
09 Step-by-step replacement
Safety first — breaker off, every time
Turn the circuit off at the breaker panel before touching anything inside the housing — not just the wall switch. Verify with your voltage tester at the unit. The fan and light share the housing, and "the switch is off" has hurt people when someone else flipped it back on.
Kill the power and remove the grilleBreaker off, tester confirms dead. Pull the grille down by its edges, squeeze the spring clips, and set it aside. Remove the bulb so it can't break.
Unplug the old motorFollow the motor's cord to the receptacle inside the housing and pull the plug straight out. Note which receptacle is the fan's — the light has its own plug.
Remove the old assemblyBack out the screws holding the mounting plate to the housing (keep them — you'll reuse them), then work the plate and wheel down and out of the housing. Mind the sharp edges.
Clean the housing while it's emptyVacuum the dust cake out of the housing and duct opening, and check the damper flap swings freely. Two minutes here is the difference between a quiet fan and a dusty one.
Seat the new assemblySlide the S0503B000 plate into the housing, align the wheel in the scroll so it spins without touching, and drive the screws snug. Spin the wheel by hand — it must turn freely with no scraping.
Plug it inPush the motor plug firmly into the same receptacle the old one used. Refit the bulb.
Test before the grille goes backBreaker on. Fan should spin up quietly; run the light too. Any scraping or wobble means the plate isn't seated — power off and re-check step 5.
Refit the grilleSqueeze the springs, push the grille home, done. Total time for most people: 10–15 minutes.
10 Cleaning & maintenance
Bathroom fans die slowly of dust. A blower wheel caked in lint moves less air, runs louder, and loads the motor — most "weak fan" complaints are this, not a dying motor.
Every 6 months: pull the grille, wash it in soapy water, and vacuum the wheel and housing with the power off.
While it's open: spin the wheel by hand. Smooth and silent is healthy; gritty, wobbling, or stiff means bearing wear — plan on the assembly before it seizes mid-shower-season.
Check the damper at the duct connection: it should flap freely. A stuck damper quietly cancels the fan's whole output.
Don't oil the motor. These shaded-pole motors use sealed bearings; oil doesn't reach them and just collects dust.
Bulb swaps: stay at or under the 100W A19 max on the housing label — or use an LED A19, which runs far cooler and draws a fraction of the power.
11 Can you upgrade it instead?
Short answer: not inside this housing. The 763RLN is a 50 CFM / 2.5-sone unit, and its airflow and noise are set by the housing, the 4″ duct, and the wheel size. A fresh S0503B000 restores it to exactly as-new performance — it cannot make it stronger or quieter than it was the day it was installed.
Want quieter? Under-1-sone fans exist, but only as complete new units with larger housings — a full replacement job (§7).
Want more CFM? An 80–110 CFM unit usually needs a bigger housing and sometimes a 6″ duct. Also a full replacement.
The 690NT kit is not an upgrade path here. Despite the similar name range, the NuTone 690NT upgrade kit fits the 693/695/696N and Broan 670/671/688/689 only — not the 763RLN (§4).
No speed controls: the manufacturer specifies this unit is not for use with solid-state speed controls, so a dimmer-style "quiet it down" hack is off the table.
If 50 CFM was never enough — the 763RLN is rated for baths up to 45 sq ft — that's a sizing problem, and the honest fix is a correctly sized new unit, not a like-for-like motor.
12 FAQ
Is the Cenipar S0503B000 the same as the genuine Broan-NuTone part?
It's an aftermarket assembly made to replace the Broan-NuTone S0503B000 — same job, same fit for the 763RLN series, from a third-party brand rather than the original manufacturer. That's why it costs less than the OEM part typically does. Fit is determined by the part number and your housing label, not by the brand on the box.
Will this fit my Broan 688?
No. The 688 is a smaller fan-only unit with a different housing and mounting pattern. It takes its own motor (or the 690NT upgrade kit). If your label says 688 or 688-K, don't order this part.
My old part says 89850000. Is this the same thing?
No — and this is the most common mix-up in this category. The 89850000 is the motor for the NuTone 665 series. Different plate, different wheel, different housing. If your label says 665, you need the 89850000-style assembly, not this one.
Do I need an electrician?
For most people, no. The motor and light in the 763RLN are plug-in by design, so the swap is unplug, unscrew, screw in, plug in — no wiring is opened. The non-negotiables are the breaker off and a voltage check first. If you find damaged wiring, a scorched receptacle, or anything that doesn't match this description, stop and call an electrician.
Can I use this fan over a shower?
The 763RLN host unit is listed as suitable over a tub or shower when it's on a GFCI-protected branch circuit. That rating belongs to the installed unit and its circuit — the replacement motor doesn't change it. If your circuit isn't GFCI-protected, that's an electrical fix, not a fan fix.
How long does the swap actually take?
About 10–15 minutes once the grille is off, for a first-timer working carefully. No ceiling cutting, no duct work, no wiring — because you're reusing the housing that's already installed.
What RPM is this motor?
Not stated consistently enough to print. Listings for this assembly variously omit the speed or quote figures that don't agree, and neither the Cenipar listing nor the 763RLN spec sheet gives an authoritative RPM for the replacement assembly. What decides fit is the part number, the plate, and the plug — and those are verified in §3–§5.
13 Sources & verification
Last verified Oct 21, 2026. Everything on this page traces to one of these — and where the sources don't agree, we say so instead of picking a number.
Host-unit specs (50 CFM, 2.5 sones, housing and grille dimensions, ratings, restrictions): the manufacturer's published spec sheet for the NuTone 763RLN.
Assembly identity, motor rating (120V / 1.0A / 60Hz), and fit list (763RLN, 763RL, 763RLNB, 763RLN-R01): the Cenipar product listing for the S0503B000 on Amazon, ASIN B0GXDJ27BG, cross-checked against the Broan-NuTone part number it replaces.
690NT kit compatibility (693, 695, 696N, Broan 670, 671, 688, 689 — not the 763RLN): the manufacturer's listing for the NuTone 690NT upgrade kit.
Price: $30.99 was the price shown for the Cenipar S0503B000 on Amazon when checked Sep 18, 2026. It is a record of that date, not a current price — use the button in the buy box for today's figure.
Known gaps & disagreements
Motor RPM: not reliably published for this assembly — omitted rather than guessed. Assembly dimensions: listings cite approximately 6.5″ × 9.5″ × 9.25″, with small variations between sellers; the dimensions that actually decide fit are the plate and wheel geometry matched to the 763RLN housing. CFM/sones are the host unit's rated figures from the manufacturer, not measurements of this aftermarket assembly.
Confirmed your label says 763RLN, 763RL, 763RLNB, or 763RLN-R01? Then this is your part.
