The short answer
Start at a cycle too short for the soil level: it is the most common cause on a machine of this kind and the cheapest to correct. Only when the load, the arms and the filter are all right does the machine itself become the suspect.
What the dishwasher is actually doing
- Results got worse gradually over months — Gradual change is build-up — limescale, grease, a slowly blocking arm — rather than a component that has failed.
- Gritty deposits left on the dishes — Debris is being recirculated rather than flushed away, which points straight at the filter and the sump.
- Dishes on the top rack clean, bottom rack poor, or the other way round — One arm is not doing its job. Which rack fails tells you which arm to look at.
- NEAR MISS — the machine will not complete a cycle — If it stops partway rather than washing badly, the cycle fault is the page to read, not this one.
Causes, most likely first on a Koolmore dishwasher
- A cycle too short for the soil level — Detergent needs heat to work. A machine fed from a cold supply spends the first part of the cycle heating water, and on a short cycle it may never reach the temperature the detergent was designed for, leaving a film and undissolved powder. Ranked ahead of the rest since it is both the likeliest and the only one that can be settled before anything is taken apart. A commercial-duty appliance meets in a month what a domestic one meets in a year, so its wear items lead and its electronics trail.
- Hard water overwhelming the detergent — Detergent loses strength in storage, particularly once a box or a bag has been open in a damp kitchen for months. The same tablet that worked last year can leave a film this year, and nothing in the machine has changed. Second, and worth checking before anything is taken apart, since it is visible from outside the machine.
- Blocked spray arm jets — The arms spray through a row of small holes, and those holes block with limescale, seeds and label fragments. As they close, the arm spins more slowly and the pattern collapses, so coverage falls away long before anything stops completely. This far down the list because it needs the two above ruled out before the evidence for it means anything.
- Filter and sump overdue a clean — A blocked filter also restricts flow to the pump, so pressure at the arms falls and coverage drops at the same time. One neglected part therefore produces two different complaints. Least likely of the four, and the one that only makes sense once the others are ruled out.
What to check first, second, third
- Check which cycle is actually being used, and how long it runs — A quick cycle on a heavy load produces exactly this complaint with nothing broken. Start at this check: it is the one most likely to end the job on its own.
- Check the rinse-aid reservoir and, if the machine has one, the salt — Spotting and wet glassware is a rinse-aid symptom far more often than a heating one. Second in order, and only worth doing once the first has come back clean.
- Take each arm off and hold it up to the light — Blocked jets are visible immediately, and a rinse under a hot tap clears most of them. Leave this one until the cheap checks are done; it is the slowest of the three.
What you can do yourself
- Run the hot tap at the sink until hot, then start the machine on a full cycle — One cycle is enough to tell whether the fill temperature was the limit.
About 15 min
- Open a fresh pack of detergent and run a normal cycle with rinse aid topped up — Old detergent is the cheapest thing on this page to rule out.
Tools: fresh detergent, rinse aidAbout 15 min
- Clean the arm bearing and the feed port before refitting — Grease on the spindle is what stops an arm turning at speed.
Tools: clothAbout 15 min
- STOP when the next thing to move is a fixing rather than a cover — Anything held by fasteners is holding something in place for a reason. Write down what you found and leave it there.
Before you touch anything
Safety
Isolate the machine at its socket or switch before working on it, and close the water supply valve under the sink before opening any fitting. Water arriving under pressure into a cupboard does more damage in an hour than the repair costs.
When this becomes a service call
Stop and call at the point where the next step would be testing a heater or a pump. Everything before that is loading, cleaning and consumables, and it fixes the large majority of poor-wash complaints.
Nearest pages of this class
What is not on this page
Read this as the class-level answer. If a page exists for your particular Koolmore line, that page is more specific and more useful for your unit, and it carries the model detail this one cannot: fastener sizes, component positions and service sequences.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
