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Quick answer
If a Hotpoint Aquarius FDM 550 cleans the bottom rack but leaves the upper rack dirty, start with the upper-rack wash path rather than assuming the filter or detergent is the whole problem. Confirm the full model suffix on the rating plate, then isolate power and check that the upper spray arm is clear, turns freely by hand, and is not blocked by a tall item or a rack/feed connection that shifted during the move. Check the accessible filter and visible sump for debris and look for an obvious external hose or installation problem, but do not remove the pump or open the dishwasher cabinet. If the lower rack still washes normally while the upper rack remains dry, gritty, or coated after those checks, the upper water-distribution or circulation path needs model-specific service; a community reply suggested a diverter issue for this exact symptom, but that is not a confirmed diagnosis. Stop immediately for a leak near electrical parts, burning smell, smoke, sparking, a hot plug, or damaged wiring.
Before you begin
Safety first
- Keep ordinary checks to the rating plate, accessible rack/load, hand rotation of an accessible spray arm with power isolated, visible filter, and obvious external installation observations. Internal pump, diverter, valve, heater, wiring, control, and live electrical work require qualified service.
Work through in order
Diagnostic checks
Use only checks that match the exact appliance or system and its official guide.
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Check 1
Before troubleshooting, photograph the rating plate and record the complete Hotpoint model suffix, serial or service information, market, and what changed after the move. From outside the appliance, note whether it is visibly tilted, whether the door closes normally, and whether the inlet or waste hose is visibly kinked or trapped. Do not pull out an integrated unit alone.
Expected result: The plate confirms FDM550P or another full suffix; only the family name FDM 550 is visible; the machine is visibly out of level or a hose is kinked; or the installation looks unchanged.
Next step: Use the exact model or 12NC in Hotpoint's manual lookup. Correct only an obvious external hose-routing or accessible alignment issue; arrange installation or appliance service if the unit must be moved, leveled, or disconnected.
Stop if: Do not order a part from the Aquarius name alone, pull out the dishwasher under a counter by yourself, or loosen water or electrical connections while water is present.
Why this matters
Why: The full identity determines which Hotpoint manual and parts information apply. A visible post-move installation issue is a more direct first lead than an internal component claim, but an unchanged installation does not rule out an upper wash-path fault.
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Check 2
With the dishwasher switched off, unplugged from a dry safe position, and cool, remove the upper rack only as the appliance permits. Inspect the upper spray arm, its holes, the rack clearance, and the visible upper water-feed or docking area. Turn the arm only by hand; clear visible food or mineral deposits with a soft non-metallic brush and refit it exactly as the matching manual shows.
Expected result: The upper arm is obstructed, its holes contain debris, it cannot rotate freely, a tall dish contacts it, the rack or feed connection is not seated, or the arm and clearance look normal.
Next step: Remove only visible deposits, rearrange the load so the arm can turn, and confirm the rack and feed connection are seated before one normal supervised cycle. If the arm is cracked, loose, or will not seat, keep the appliance out of use and request model-specific service.
Stop if: Do not use a sharp metal tool, dismantle a feed tube, remove the pump guard, or run the machine with a loose or missing spray arm.
Why this matters
Why: A blocked arm or loading/clearance problem can prevent water from reaching the upper rack even while the lower rack appears normal. If the arm and loading path are clear, the symptom shifts toward water distribution or circulation rather than a simple loading error.
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Check 3
After the arm and load are corrected, inspect the accessible filter assembly and visible sump area with power isolated. Remove only loose, reachable debris and refit the filter securely. After a completed cycle, compare the upper-rack result with the lower rack: note whether the upper items are wet but gritty, mostly dry, or washed normally while the lower rack remains clean.
Expected result: The filter is clogged or loose; debris is visible in the accessible sump; both racks are poor; the lower rack is clean but the upper rack is wet and gritty; or the upper rack is unusually dry while the lower rack cleans.
Next step: Clean and lock the accessible filter, then stop repeating cycles if the upper-only symptom persists. Record the result for service rather than opening the pump, testing live parts, or guessing a replacement component.
Stop if: Do not reach into a hidden pump, remove a guard, perform a live electrical test, or operate if standing water is reaching electrical connections.
Why this matters
Why: A dirty filter or broad circulation problem can affect both racks. A clean lower rack with a wet but dirty upper rack keeps an upper spray/distribution problem in play, while an unusually dry upper rack makes missing or weak upper water delivery more concerning. None of these observations identifies a pump, valve, or diverter part by itself.
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Check 4
If the upper arm, load, filter, and visible installation are normal, record any other cycle symptoms without dismantling the machine: filling sound, spray or circulation sound, drain completion, error lights, leaks, unusual vibration, and whether the problem began only after relocation. Do not open the door during a running cycle as a spray test and do not restart repeatedly to chase an intermittent fault.
Expected result: The machine fills and drains but the upper rack remains the only problem; the dishwasher has weak or absent circulation, poor filling, standing water, an error indication, a leak, or an abnormal sound.
Next step: Provide the complete model, market, move timeline, rack-by-rack result, and observations to Hotpoint or a qualified dishwasher technician. Keep the appliance isolated if there is a leak, electrical symptom, or repeated fault.
Stop if: Do not run a diagnostic sequence copied from another Hotpoint model, bridge a safety device, remove panels, or probe energized wiring.
Why this matters
Why: Normal filling and drainage with a clean lower rack narrows the useful service description to upper water distribution or circulation, but it still does not prove a diverter or pump failure. A whole-machine symptom points to a broader water, drain, or service issue.
Use your observations
Decision map
Find the observation that best matches what you see, then follow the next safe action.
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PATH 01Next step
What you see
The upper spray arm has blocked holes, cannot rotate freely, contacts the load, or the rack/feed connection is visibly out of position after the move.
Do this next
Clear only visible deposits, reload the rack, and reseat the accessible arm or rack connection exactly as the matching manual shows. If it will not seat or is damaged, arrange service.
Why this path and its safety boundary
Why it matters: An accessible upper wash-path or loading issue is more likely than a confirmed internal failure.
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PATH 02Next step
What you see
The upper arm and load are clear, the filter is secure, the lower rack still cleans, and the upper rack remains wet-but-gritty or unusually dry on a normal cycle.
Do this next
Stop part-swapping and ask Hotpoint or a qualified dishwasher technician to assess the upper distribution/circulation path against the complete model identity. Do not open the pump or select a diverter, pump, or control part from this symptom alone.
Why this path and its safety boundary
Why it matters: The pattern is consistent with insufficient upper water delivery or distribution. A Reddit reply suggested a diverter for the matching FDM 550 symptom, but that is a hypothesis rather than an established diagnosis.
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PATH 03Next step
What you see
Both racks are poorly washed, filling or draining is abnormal, standing water remains, or an error, leak, unusual vibration, or circulation noise appears.
Do this next
Stop normal cycles, correct only an obvious safe external hose issue, and arrange model-specific service with the recorded observations. Keep power and water isolated when a leak or electrical hazard is present.
Why this path and its safety boundary
Why it matters: The issue is no longer isolated to the upper-rack wash path and may involve water supply, drainage, installation, or an internal fault that the supplied evidence cannot identify safely.
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PATH 04Next step
What you see
The exact model suffix or market cannot be confirmed, or an FDM550P procedure does not match the appliance in front of you.
Do this next
Use the rating plate and 12NC to retrieve the matching Hotpoint manual or have Hotpoint service identify the unit. Until then, limit checks to safe external observation and accessible cleaning.
Why this path and its safety boundary
Why it matters: The evidence is not sufficient to transfer model-specific parts, service modes, or installation instructions across Hotpoint variants.
Helpful context
Understand the symptom
The recent move is useful timing information, not proof that a particular part failed. A dishwasher can have a blocked or obstructed upper spray path, a rack or feed connection that is not seated as before, or a broader circulation problem. The key distinction is whether the upper arm is clear and able to rotate, whether the upper rack is receiving water, and whether the lower rack still cleans normally.
The supplied identity is Aquarius FDM 550, while Hotpoint's current official parts page exposes an FDM550P model entry. Treat that as a model-family lead, not permission to order a part or apply another suffix's service procedure. Use the complete rating-plate model and the Hotpoint manual lookup before any model-specific work.
When checks do not resolve it
Need a professional?
Request model-specific Hotpoint or qualified dishwasher service when the lower rack cleans but the upper rack remains dirty after safe checks, when the exact model does not match the available instructions, or whenever a leak, electrical symptom, error, or whole-machine wash failure appears.
Safety scope: Keep ordinary checks to the rating plate, accessible rack/load, hand rotation of an accessible spray arm with power isolated, visible filter, and obvious external installation observations. Internal pump, diverter, valve, heater, wiring, control, and live electrical work require qualified service.
Have this ready
- Provide the complete model suffix or 12NC, market, serial information, move or reconnection date, whether the lower rack still cleans, the upper rack's wet/gritty/dry result, filter and spray-arm observations, hose or leveling observations, error lights, and photographs of the rating plate and visible installation.
Common questions
FAQ
Why does the bottom rack clean while the upper rack does not?
That pattern points first to the upper spray arm, rack loading or clearance, the visible upper feed connection, or upper water distribution. It does not by itself prove a failed pump, diverter, valve, or control. Check the accessible upper path with power isolated, then arrange service if the upper-only result persists.
Could moving the Hotpoint FDM 550 have caused the problem?
The timing makes installation or a shifted rack/feed connection worth checking, but it is not proof of causation. Confirm the full suffix, look for a visible hose kink, tilt, or damage, and do not pull out an integrated dishwasher alone.
Should I replace the diverter or pump?
No. A Reddit reply raised a diverter as a possibility for this exact symptom, but the thread did not confirm the repair and the symptom cannot identify a part safely. Have the complete model and upper-rack result assessed before any part is selected.
When should I stop using the dishwasher?
Stop for a leak near electrical parts, burning or electrical odor, smoke, sparking, a hot or damaged plug, exposed wiring, repeated breaker trips, or a serious filling or draining fault. Isolate power and water only from a dry, safe position and arrange qualified service.
Read the exact guide
Official sources
- Official Hotpoint Appliance Service Repair - HotpointHotpoint UK Appliances Limited · Supports escalation to Hotpoint dishwasher service when safe external checks do not resolve the symptom; it does not identify a failed component.
- Spare parts for Hotpoint: Model FDM550P - 37544450000Hotpoint UK Appliances Limited · Exact official FDM550P model catalogue entry; it supports identity and compatibility verification, not an assertion that every Aquarius FDM 550 suffix shares the same part.
- Hotpoint dishwasher only cleans things on the bottom rackReddit, r/appliancerepair · Exact community post matching Hotpoint Aquarius FDM 550, recent move into a house, clean lower rack, and dirty upper rack; replies are hypotheses and not manufacturer confirmation.
- Hotpoint Appliance ManualsHotpoint UK Appliances Limited · Official Hotpoint UK manual lookup workflow; it supports confirming the exact model and market, not a universal diagnosis for every Hotpoint dishwasher.
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