The short answer
On the COSDWV family the usual reason a Cosmo dishwasher is leaving dishes dirty is filter and sump carrying old debris, and that is where the order below departs from the brand-generic article one level up: on the manual-filter build it outranks spray arms blocked or not turning freely. The check that confirms which build you have is simple — lift the lower basket and look at the sump: a removable cylinder and a flat mesh plate means the filter is yours to clean and nothing grinds debris for you. Arms, filter, dispenser, loading and programme are owner work; anything under the sump is not.
What you observe on these models
- Dishes clean but soaking wet at the end — A drying complaint rather than a cleaning one, and rinse aid is the first thing to check.
- Gritty film on everything in the load — Evenly distributed, which points at the water being dirty rather than the spray being blocked.
- Greasy film that wipes off with a finger — Heat rather than mechanics: fats need temperature to move at all.
- White cloudiness on glassware — Mineral film if it clears with a weak acid, etching if it does not.
- One shelf clean and the other dirty — A sector problem, which only a spray path can produce.
- NEAR MISS — water standing in the sump at the end — That is a drainage fault, and the drainage page is the right one to read.
Causes, most likely first on the COSDWV family
- Filter and sump carrying old debris — Ranked first here: the wash water is recirculated, so the filter is the only thing standing between last night's debris and tonight's plates. Once it is loaded the machine is washing with dirty water and redepositing what it removes.
- Spray arms blocked or not turning freely — Second: everything the machine does, it does with two or three spinning arms. A jet plugged with a seed or a label, or an arm fouled by a handle hanging through the basket, takes a whole sector of the load out of the wash while everything else looks normal.
- Scale and hard-water film — Third: it ranks here because the test is definitive: a cloudy glass that clears with a weak acid rinse is scale, and one that does not is etching, which is permanent.
- Rinse aid empty — Fourth: rinse aid is what makes water sheet off rather than bead, and without it the load comes out spotted and wet even when it is perfectly clean.
- Detergent type, dose or a blocked dispenser flap — Fifth: a flap held shut by a tall item releases the detergent at the end of the cycle instead of the start, which reads exactly like a machine that has stopped cleaning.
- Loading that shadows the spray — Sixth: water travels in straight lines.
Check in this order, and why
- Lift out the filter and look at the sump beneath it — A loaded filter means the machine is washing with dirty water and redepositing it.
- Spin each arm by hand and look through the jets — Seconds to do, and it is the only cause that produces one clean shelf and one dirty one.
- Try a weak acid rinse on one cloudy glass — Cloudiness that clears is scale; cloudiness that stays is etching and is permanent.
- Check the rinse-aid reservoir — Empty, the load comes out spotted and wet even when it is genuinely clean.
Before you open anything
Safety
Switch the machine off at its spur or unplug it, and shut the isolating valve under the sink, before anything is opened — water and mains wiring sit close together under this cabinet. Never defeat the door latch to watch a cycle run with the door open; that interlock stops a hot spray at head height. Bail standing water out before tipping the machine, and expect glass in the sump, so feel with a cloth rather than bare fingers.
Models in the COSDWV family
Reference| Model number | Family key |
|---|---|
| COS-DWV24TTR | cosmo:dishwasher:cosdwv |
When to call a technician
Bring someone in once a full hot programme on a correctly loaded machine with a clean filter still leaves food on the dishes. Call sooner if the wash sounds obviously weaker than it used to, because a failing circulation pump gets worse rather than better and it takes the heater element with it on some machines.
Other pages for this family and brand
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