Thermador dishwashers are quiet, and quiet machines hide their symptoms. By the time an owner calls us, the machine has usually been degrading for a year, and the useful part of the call is working out which of its four subsystems — wash, heat, drain, door — has actually changed.
Grit on the top rack only
This is the single most diagnostic complaint a dishwasher owner can give us, because it localises the problem before we open the door.
Water reaches both racks from the same pump. If the lower rack is being washed properly, the pump, the inlet valve, the heater and the cycle are all doing their jobs, and the fault is downstream in the path that serves the rack that is not getting clean.
The upper arm is fed through a column at the back of the tub and spins on its own bearing. Its holes are angled to throw water outward and upward across the rack, and the holes toward the outer end cover the perimeter — the glasses at the corners, the bowls at the ends. Those are the holes that suffer first, because pressure falls along the arm from the centre outward and the outer end has the least margin to lose. They close one at a time, over years. The arm still spins. It still sounds exactly as it always did. It still washes the middle of the rack.
The other candidate is the filter. Thermador’s filter assembly is fine-meshed by design, which is what makes the machine quiet and thorough, and it is also what makes it an efficient trap. A filter that has not been out in two years starves the pump, and the upper arm — furthest from it, lowest in pressure margin — is the first thing to feel it.
Both of those are checks an owner can make. Take the arm off, hold it to the light, count the holes you can see through, and compare the outer third with the inner. Take the filter out while you are there.
Standing water and long cycles
Water left in the sump is a drain problem, and the order of suspicion is: the filter, then the drain hose loop, then the air gap or disposer connection, then the drain pump. The disposer knockout plug is worth naming — a dishwasher plumbed into a disposer whose knockout was never punched out will not drain at all, and we have found that on installations that ran for years because the machine was replaced and the plumbing was not revisited.
A cycle that stretches out is usually a heating problem, and it is a misunderstood one. The machine will not advance until the water reaches temperature, so a weak heater turns a two-hour cycle into a four-hour one without ever reporting a fault. The owner reads it as the machine being slow. It is the machine waiting. A cycle time recorded from a cold start, on an empty machine, on the same programme twice, is a genuinely useful number to bring us.
Films on glassware
Two different films get reported as the same complaint and they need separating.
The first wipes off, or clears after an acid cycle. It is deposit sitting on the surface, and it is a matter of rinse aid, detergent dose and load size rather than a fault in the machine.
The second does not come off, ever. That is etching — damage to the glass surface itself — and neither we nor anyone else can recover an etched glass. It is worth knowing which one you have before changing anything, because the instinctive response to film is more detergent, and over-dosing is how film becomes etching. Keep the rinse-aid reservoir filled and dose for the load actually in the machine rather than for the worst load you ever run.
Doors, seals and hinges
A door that drops instead of holding position has a spring or a cable at fault, and it is worth fixing promptly because the same slack lets the door sit off square against the seal. A slow leak at the bottom of the door is nearly always the seal, the door alignment, or debris caught in the seal channel — rarely the tub.
On a flush-fit installation the door also carries a custom panel, and its weight is what the spring was balanced against. A panel changed during a kitchen refresh without the spring being retensioned will make a perfectly good door behave like a failing one.
Access and the part
A dishwasher is serviced in place far more often than owners expect: the filter, both arms, the sump, the heater and the door assembly are all reachable through the front. Pulling the machine is necessary for the drain pump, the inlet valve and anything at the rear connections, and that needs the toe-kick off, the supply and drain accessible, and the flooring in front protected — on a fitted run with stone returned tight to the appliance it is the slow part of the job.
Photograph the rating plate before you call. Pumps, arms and door components change across production runs, and the serial number is what lets us check availability before the van is loaded.
What a visit involves
We pull the filter and both wash arms, hold the arms up to the light and count what is actually open. We check the heater, the drain path and the door seal before anything electronic is considered. Flat $80 diagnostic, credited toward the repair. Written estimate first. Genuine OEM parts, 90 days on labor and 365 days on parts.