Commercial Dishwasher Not Heating or Drying Properly: Here’s How to Fix It

Commercial dishwashers are the backbone of any busy kitchen, ensuring that dishes, glasses, and utensils are clean, sanitized, and ready for use. When a dishwasher stops heating or drying properly, it can create significant operational challenges. Plates come out wet, greasy, or unclean, staff must hand-dry items, and service efficiency can drop dramatically, leading to frustration and lost revenue.

A common culprit behind these issues is a problem with the heating system. Components like the dishwasher heating coil, thermostat, or control board may fail over time, reducing the machine’s performance. In this article, we’ll guide you through the most common causes of heating and drying problems, how to troubleshoot them, and practical steps for resolving these issues efficiently.

How the Dishwasher Heating System Works

The dishwasher heating coil is essential for heating water and aiding in drying, making it key to diagnosing performance issues.

Commercial dishwashers typically use two heating stages:

1. Washing and Rinsing: The coil heats water to eliminate grease, food residue, and bacteria.

2. Drying Cycle: Heat from the coil evaporates moisture, leaving dishes clean and dry.

If the heating coil or associated components fail, the dishwasher may run cycles with cold water, leave dishes wet, or prevent drying altogether.

Common Reasons Your Commercial Dishwasher Isn’t Heating or Drying Properly

Struggling with a commercial dishwasher that won’t heat or dry? Here’s what’s causing it

Faulty Dishwasher Heating Coil

Over time, the dishwasher heating coil can wear out or corrode, causing the dishwasher to run cycles without fully heating or drying. Dishes may come out cold, wet, or with residue.

Fix:

• Turn off the power to the dishwasher.

• Test the coil for continuity using a multimeter.

• Replace the heating coil if it shows no continuity, using an OEM-approved part.

Thermostat Malfunction

A faulty thermostat can prevent the dishwasher from reaching the required water temperature. If the thermostat is not functioning correctly, dishes may not be sanitized, and drying may be incomplete. You may notice lukewarm water or dishes that are consistently wet at the end of the cycle.

Fix:

• Test the thermostat with a multimeter or thermometer.

• Replace it with a model compatible with your dishwasher if readings are inaccurate.

Control Board or Timer Issues

The control board manages the dishwasher’s electrical functions, including heating. If damaged, it can prevent power from reaching the heating coil, resulting in the dishwasher remaining cold or stopping mid-cycle.

Fix:

• Inspect the control board for burn marks, corrosion, or loose connections.

• Replace the board if necessary; professional service is recommended.

Broken High-Limit Switch

The high-limit switch prevents overheating, but if it fails, it can cut power to the heating coil, causing cold washes or incomplete drying.

Fix:

• Replace the switch if it is defective.

Insufficient Water Level or Pressure

Low water levels or insufficient water pressure can leave the heating coil partially exposed, reducing heating efficiency. This may cause dishes to remain cold or poorly cleaned at the end of a cycle.

Fix:

• Inspect the water inlet valve for blockages or buildup.

• Ensure water pressure meets the manufacturer’s requirements.

Why Proper Heating and Drying Matter
Maintaining the correct water and drying temperatures is essential in commercial kitchens to ensure dishes are sanitary and workflow remains efficient. If a dishwasher isn’t heating properly:

• Bacteria and residue may remain on dishes.

• Drying times increase, slowing kitchen operations.

• Energy consumption rises due to extended cycles. 

How to Ensure Proper Heating and Drying: 

1. Check Power Supply: Ensure the dishwasher is properly connected and the circuit breaker has not tripped.

2. Inspect the Heating Coil: Look for visible damage, scaling, or corrosion. Test continuity with a multimeter.

3. Verify Thermostat Functionality: Measure water temperature during a wash cycle to confirm it reaches the required heat level.

4. Run a Test Cycle: Observe whether water heats up and dishes dry correctly. Note any error codes.

5. Clean and Descale Regularly: Hard water buildup can insulate the heating coil, reducing performance. Use a dishwasher-safe descaler monthly.

Regular maintenance and timely repair of the heating coil and associated components ensure optimal sanitation, efficiency, and compliance with health standards.

Preventive Maintenance Tips

Regular maintenance keeps your commercial dishwasher running efficiently and extends the life of key components.

• Schedule professional maintenance quarterly to inspect the heating coil, thermostat, and wiring.

• Clean filters, spray arms, and nozzles to prevent blockages.

• Use detergents approved for commercial dishwashers to prevent coil corrosion.

• Monitor water quality and consider a water softener if mineral buildup is frequent.

Consistent preventive care extends the life of your dishwasher heating coil and keeps your kitchen running smoothly.

When to Replace the Dishwasher Heating Coil

Even with proper maintenance, heating coils can wear out. Signs that replacement is needed include:

• Dishes consistently come out cold or wet.

• Visible scaling or corrosion on the coil.

• Frequent tripping of the high-limit switch.

• Error codes indicating heating failure.

Prompt replacement prevents further damage and restores full efficiency to your commercial dishwasher.

A commercial dishwasher that fails to heat or dry properly is more than an inconvenience; it’s a potential hygiene and operational risk. Understanding the role of the dishwasher heating coil and other key components helps you troubleshoot issues quickly and reduce downtime. Regular inspections, descaling, and replacing worn parts ensure your dishwasher operates efficiently, keeps dishes sanitary, and complies with health regulations.

Looking for high-quality dishwasher replacement parts? PartsFe offers genuine heating coils, thermostats, valves, and control components, built for durability and optimal performance. Keep your dishwasher running efficiently and ensure sparkling, sanitized results every cycle.

FAQs

How long does a dishwasher heating coil last?
Typically, a heating coil lasts between 3 to 7 years, depending on usage and maintenance. Regular cleaning and descaling can extend its life.

Can I replace a dishwasher heating coil myself?
If you have basic electrical knowledge and the correct part. For commercial units, hiring a qualified technician is recommended to ensure safety and compliance.

Why does my dishwasher heat water but not dry dishes?
This could be caused by a faulty thermostat, control board, or drying fan. Even if the heating coil is working, these components are essential for proper drying.