Commercial Dishwasher Heating Coil Not Working: Fix It Now

 

A commercial dishwasher is an essential asset in any restaurant, cafe, or food service establishment. It ensures cleanliness, hygiene, and efficiency in daily operations. But what happens when your commercial dishwasher stops working? Without proper heat, dishes don’t get cleaned effectively, which could result in health code violations, unhappy customers, and costly downtime.

If your commercial dishwasher is not heating, the issue could be related to the commercial dishwasher heating coil—a crucial component responsible for elevating water temperature to the optimal level for sanitizing dishes. In this comprehensive guide, we'll explore the common causes behind a dishwasher heating problem, how to diagnose issues with the heating coil, and solutions to get your machine back up and running quickly.

Why Is the Commercial Dishwasher Heating Coil Critical?

Before diving into troubleshooting, it’s important to understand the role of the dishwasher heating coil in your commercial unit. This heating element warms the water during the wash and rinse cycles, typically reaching temperatures of 140°F to 160°F (60°C to 71°C). This heat not only helps break down grease and food residues but also ensures that bacteria and germs are effectively killed during the sanitization process. Without a functioning heating coil, the water remains cold or lukewarm, reducing the dishwasher’s cleaning efficiency and potentially leaving dishes dirty or unsafe.

Diagnosing the Commercial Dishwasher Heating Coil

To precisely identify if the dishwasher heating coil is the primary source of the problem or whether another component is at fault, we will guide you through a thorough, step-by-step diagnostic procedure in this section. To ensure prompt repairs and reduce downtime, this expert guide will assist operators, maintenance professionals, and facility managers in understanding the procedure.

1. Ensure Safety Before Beginning

Before starting any diagnostic procedure, prioritize safety. Commercial dishwashers operate on high voltage and involve water, which makes safety precautions essential:

  1. Turn off the power at the circuit breaker to eliminate the risk of electric shock.

  2. Unplug the dishwasher if possible.

  3. Wait for the unit to cool down completely before touching internal components.

  4. Wear protective gloves and safety goggles, especially if you need to work near water connections or heating elements.

2. Observe Initial Warning Signs

Begin with a visual and operational inspection. Look for the following signs, which commonly indicate a heating issue:

  1. Dishes feel cool or lukewarm at the end of the cycle.

  2. There is no steam during or after the cycle.

  3. The dishwasher runs longer than usual, as it may be compensating for the lack of heat.

  4. Error codes or indicator lights appear on the control panel (refer to the manufacturer’s manual).

  5. Residue or food particles remain on dishes after a full wash.

Although these signs suggest a heating problem, they don’t confirm the heating coil is the issue, which brings us to the next steps.

3. Access the Heating Components

To physically inspect the heating coil, you will need to remove specific panels on the dishwasher. This process may vary by brand and model but generally includes

  1. Unscrewing the access panel at the bottom front or rear of the unit.

  2. Carefully remove the kickplate or base cover to gain access to the electrical components.

Once the internal wiring and coil area are visible, proceed with caution to avoid damaging fragile components.

4. Visual Inspection of the Heating Coil

With the heating element now accessible, perform a thorough visual inspection:

  1. Check for physical damage such as warping, discoloration, or burn marks.

  2. Look for signs of corrosion or mineral buildup, especially in areas with hard water. Mineral deposits can reduce the coil’s ability to conduct heat effectively.

  3. Inspect wiring connections to ensure they are not loose, burnt, or melted.

If you notice any obvious physical damage, it’s likely that the dishwasher heating coil needs replacement. If not, continue with electrical testing.

5. Test for Electrical Continuity

Testing the heating coil with a multimeter is a crucial step to determine if the component is functioning properly.

  1. Set your multimeter to the ohms (Ω) or continuity setting.

  2. Detach the wires connected to the heating coil terminals to avoid interference.

  3. Place one probe on each terminal of the coil.

  4. A functional heating coil typically shows a resistance reading between 10 and 50 ohms, depending on the model. 

  5. If the reading is infinite or zero, the coil is either broken (open circuit) or shorted and must be replaced.

Additionally, some heating coils may be grounded. If you suspect a short to ground, test by placing one probe on a terminal and the other on the coil's metal casing. Any continuity detected here indicates a grounding fault, requiring immediate replacement.

6. Inspect the High-Limit Thermostat

Even if the coil itself is intact, a malfunctioning thermostat can prevent the heating element from activating.

  1. Locate the high-limit thermostat (usually mounted near the coil).

  2. Use your multimeter to test for continuity.

  3. If the thermostat is open when the unit is cool, it may be faulty.

Some dishwashers have manual reset thermostats. If tripped, they need to be reset before the coil can function again. Consult your model's manual for reset instructions.

7. Evaluate the Control Board and Heating Relay

If both the heating coil and thermostat are functioning correctly, the next component to examine is the control board:

  1. Modern dishwashers use a control board to manage various operations, including when and how long the heating coil is activated.

  2. A failed heating relay or damaged circuitry on the board may prevent the coil from receiving power.

This step often requires advanced electrical knowledge or the assistance of a professional technician. Control board diagnostics vary by manufacturer and may require proprietary tools or software.

8. Check for Sensor or Probe Failures

Some commercial dishwashers use temperature sensors or thermistors to monitor water temperature. If these sensors fail or provide inaccurate readings, the system may not send the signal to energize the heating coil.

  1. Test the sensor’s resistance and compare it to manufacturer specifications.

  2. Faulty sensors must be replaced to restore accurate temperature regulation.

9. Run a Full Diagnostic Cycle

Once all physical and electrical tests are complete and repairs or replacements are made, reassemble the dishwasher and restore power. Run a diagnostic or service cycle (if your machine supports one) to:

  1. Confirm that the heating coil activates correctly.

  2. Monitor temperature rise using a thermometer or built-in diagnostic display.

  3. Verify that no error codes reappear during the cycle.

How to Repair for Commercial Dishwasher Heating Coil Issues

Repairing a commercial dishwasher's heating issue begins with correctly identifying and addressing a faulty heating coil. The process requires attention to safety, proper tools, and a clear understanding of your dishwasher's model. Follow these repair steps:

1. Safety First: Power Down

Unplug the dishwasher or turn off the circuit breaker before working on the unit to avoid electrical shock.

2. Remove Access Panels

Use a screwdriver to remove panels protecting the heating element and other internal components.

3. Disconnect the Heating Coil

Carefully detach the wires connected to the heating coil. Take note of or photograph the connections to ensure proper reinstallation.

4. Remove the Heating Coil

Unscrew or unclip the coil from its housing. Depending on your dishwasher model, this process may vary.

5. Install the New Heating Coil

Obtain the exact replacement heating element compatible with your dishwasher. Install it by securing it in place and reconnecting the wires.

6. Reassemble and Test

Replace access panels, restore power, and run a test cycle to confirm the dishwasher heats properly.

A commercial dishwasher that isn't heating poses a serious risk to kitchen efficiency and hygiene. The dishwasher heating coil is essential for reaching the high temperatures needed to properly sanitize dishes. Identifying and addressing heating issues early can prevent costly repairs and ensure compliance with health standards. Regular maintenance and timely repairs increase the longevity of your equipment but also keep operations running smoothly. Understanding how the heating coil functions—and knowing when to act—helps avoid service disruptions. Don’t let cold, unsanitized dishes impact your business. Act quickly to resolve your commercial dishwasher heating issue and maintain peak performance.

Written by Allen Rode for PartsFe, your trusted source for a variety of high-quality commercial dishwasher parts, including dishwasher heating coils and drain pumps.

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