The short answer
Film, grit and wet plastics are three different complaints on the Caf PDT family and they do not share a cause. The matrix below lists two model tags that differ only in their trailing revision characters, so a part that suits one usually suits its neighbours, and the tag still decides. Grit is spray and filtration, white film is water hardness and rinse aid, wet plastics are the drying system doing exactly what it is designed to do on a low-energy cycle.
What you can observe on these models
- Baked-on soil on items that used to come clean — A gradual change like this is accumulation in the filter or the sump rather than a component failure.
- A burnt or stale smell from the tub — Soil retained in the filter between cycles. It is the same cause as the grit, seen from a different sense.
- Cycle time has got noticeably longer — The control is extending the cycle to reach its target temperature, which points at incoming water temperature or the heater.
- Gritty residue on the underside of bowls and cups — Soil that was washed off and then redeposited, which means filtration rather than spray pressure.
- NEAR MISS — dirty water left standing in the tub — That is a drain fault, not a wash fault, and the drainage page covers it. Cleaning cannot be judged until the tub empties.
Causes, most likely first on this family
- Spray arms blocked or unable to turn — First on these models — a tall item in the rack stops the upper arm on the first quarter turn and the load below it stays dirty.
- Filter and sump screen fouled with soil — Second: a packed filter recirculates what it should be trapping, which is exactly what produces grit on the undersides.
- Wash water not hot enough — Third because it is easy to test — draw hot water at the sink before starting — and it explains poor results on short cycles.
- Detergent type, dose or an empty rinse aid reservoir — Fourth: hard water needs more detergent than soft, and rinse aid is what makes the difference between dry and spotted.
- Wash pump, diverter or heating element — Last on this platform because everything above it is cheaper to prove and far more likely.
Check in this order, and why
- Compare the top and bottom racks after a load — A clean bottom with a dirty top isolates the upper arm feed and the diverter immediately.
- Reload the machine deliberately and run it again — Tall items, nested bowls and a blocked dispenser produce a dirty load on a perfectly healthy machine.
- Clean the filter, then run an empty hot cycle — This clears the sump and gives the next diagnosis a clean starting point.
- Listen through the wash for the diverter changing — A change in pitch as pressure shifts between arms is normal on this platform; a constant note is a reason to call.
Before you open anything
Safety
Switch the dishwasher off at its breaker before removing the filter housing, the sump cover or any panel — a capacitor can hold a charge after the power is off. Broken glass in the sump is the real hazard on the Caf PDT family: use a gloved hand or a wet-vac rather than fingers, and never run a cycle with the filter removed.
Models in the PDT family
Reference| Model number | Family key |
|---|---|
| PDT75***R*** (v7) | caf:dishwasher:pdt |
| PDT755**V*** | caf:dishwasher:pdt |
When to call a technician
Call when the complaint is sudden rather than gradual: a machine that cleaned yesterday and not today has lost a component, not a habit. On these models that means the wash pump, the diverter or the heating circuit, none of which are owner-testable. Call also if the tub never gets warm, since a dead heater turns every cycle into a cold rinse.
Other faults covered for this family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
