Commercial Commercial Dishwasher Troubleshooting, Repair & Maintenance
Compiled by Resultex Media Group · Editorially reviewed · Last verified August 2026
Pick the problem you’re having for a manufacturer-sourced diagnosis, or use the preventive-maintenance schedule below to avoid the call in the first place.
Common problems — pick your symptom
Preventive maintenance schedule
| Task | How often | How | Who |
|---|---|---|---|
| Clean the drain / scrap screen and empty the scrap tray | Daily, and during service (hourly if very busy) | Remove the drain/scrap screen and rinse all debris off at the sink or with the pre-rinse hose (do not bang it on the table). Empty and rinse the scrap tray/accumulator. Reinstall the screen in its proper position. | DIY-safe |
| Clean the wash and rinse arms and jets | Daily | Remove the upper and lower arms, clear each spray jet with a toothpick, and flush the arm at the sink (the stainless end plug can be unscrewed to rinse the tube). Reinstall the arms fully seated so spray reaches all ware. | DIY-safe |
| Clean the pump intake screen and sump | Daily / at end of day | Drain the machine, remove the scrap screen, and inspect and clean the pump-intake screen in the sump so the wash pump gets full flow. | DIY-safe |
| Check wash and final-rinse temperatures | Daily (log per health-department practice) | Read the wash and rinse thermometers. Low-temp machines: wash tank at least 120°F, incoming 120-140°F. High-temp machines: final sanitizing rinse at least 180°F at the manifold (165°F for stationary-rack single-temp), utensil surface reaching 160°F. Verify high-temp sanitizing with a maximum-registering thermometer or heat-sensitive label at the dish surface. | DIY-safe |
| Test the sanitizer concentration (low-temp machines) | Daily / per shift | Run a cycle and test the final rinse at the surface of the ware with chlorine test strips. Concentration should be at least 50 ppm (target 50-100 ppm; some jurisdictions require 100 ppm minimum). Adjust the pump/cam or call the chemical supplier if out of range; never exceed a 6% sodium hypochlorite sanitizing solution. | DIY-safe |
| Check and prime the chemical supplies (detergent / rinse aid / sanitizer) | Daily / before service | Confirm each container has product and the correct color-coded line is in each bottle (CMA: red = detergent, blue = rinse aid, clear/white = sanitizer). Use tube stiffeners so feed tubes don't curl and suck air. Prime each pump until product discharges, and watch the injection tubes during a cycle. | DIY-safe |
| Maintain water treatment / softener | Ongoing (check salt regularly) | Keep incoming water treated to about 3.5 grains-per-gallon or softer to prevent spotting, film, and scale; keep the softener charged with salt. High iron may need an iron filter; high chlorine in the supply may need a chloride-removal system. | Basic |
| Delime / descale the machine and booster | Periodically (when lime buildup is found; more often in hard-water areas) | Have the tank, wash arms, jets, and booster delimed/descaled. Deliming acids are highly caustic — this must be done by a qualified chemical specialist, not general staff. | Technician |
| Wipe down and inspect for leaks | Daily at cleanup | Wipe the machine down, check chemical levels, and inspect for leaks, loose end plugs, or anything that could fail during a rush. | DIY-safe |
General safety
- A commercial dishwasher must sanitize, not just wash: high-temp machines need a final rinse of at least 180°F (165°F for stationary-rack single-temp) reaching a 160°F utensil surface; low-temp machines need at least 50 ppm chlorine (50-100 ppm). A machine that can't do this is a health-code failure - sanitize ware in a three-compartment sink until it's repaired.
- Test daily: verify high-temp sanitizing with a maximum-registering thermometer or heat-sensitive label, and low-temp sanitizer with chlorine test strips. Keep an accurate thermometer/test kit on hand as the FDA Food Code requires.
- Never mix chemicals - deliming acid mixed with chlorine sanitizer (bleach) releases toxic chlorine gas. Store and feed detergent, rinse aid, sanitizer, and delimer separately.
- Deliming/descaling agents are highly caustic; heavy deliming and booster/plumbing descaling must be done by a qualified chemical specialist with proper PPE.
- The booster heater, tank heaters, high-limits, wash and drain pumps, solenoid valves, timers, relays, and all wiring are for a qualified service technician - do not open, adjust, bypass, or bridge them. Hard-plumbed water and drain connections are a plumber's job.
- Before servicing or moving the machine, turn off the power at its breaker/master switch and shut off the water supply.
- Keep water off the floor - overflow and leaks are a slip hazard (OSHA) and a contamination/pest risk near clean-side storage.
- Handle sanitized ware only by non-food-contact surfaces, let it air-dry inverted (do not towel-dry), and store it elevated and protected from splash, per the FDA Food Code.
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Sources
- CMA Dishmachines EAH/EC/3-Door Owner's Manual (Installation & Operation, Rev 1.03) - troubleshooting, cleaning, chemical feed, 50-100 ppm chlorine, wash/rinse temperatures — source
- CMA Dishmachines - How to Troubleshoot & Repair Commercial Dishwasher — source
- Hobart Dishwasher Troubleshooting Guide (Parts Town resource center) — source
- Jackson 24A-AF Instruction Manual - Troubleshooting Guide (ManualsLib) — source
- Jackson Dishwasher Troubleshooting (Parts Town resource center) - spotting/hard water, leveling — source
- Champion UH130 Installation/Operation Manual with Service Replacement Parts - Maintenance & Troubleshooting (ManualsLib) — source
- Champion Dishwasher Troubleshooting (Parts Town resource center) — source
- FDA Food Code - mechanical warewashing sanitization: hot water rinse temperatures (4-501.112), utensil surface 160°F (4-703.11), chemical/chlorine sanitizer concentration 50-100 ppm (4-501.114), test devices (4-302.14 / 4-501.116) — source
- NSF/ANSI 3 - Commercial Warewashing Equipment (sanitization performance standard for dish machines) — source
- OSHA - restaurant/foodservice hazards (wet-floor slips, chemical handling) — source