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Why is a Commercial Dishwasher Not Drying Properly?

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The dishwasher is one of the essential appliances in hotels and restaurants since many dishes must be washed before each meal is served to customers. A problem occurs when the dishwasher stops drying the dishes, which leads to a mess. Most technicians get complaints from managers of restaurants and hotels about their dishwashers not drying correctly.

To help out technicians, we're here with some significant reasons and tips to fix a dishwasher when it stops drying dishes. 

Without further ado, we'll move forward. 

What is a Commercial Dishwasher? 

Dishwashers are mainly used to wash dishes and cutlery. A dishwasher aims to eliminate manual scrubbing of dishes and save both time and effort. Generally, commercial dishwashers are used in hotels and restaurants, where numerous dishes need to be washed quickly. 

High-temp commercial dishwashers wash dishes with hot water (150-160 degrees Fahrenheit) and then rinse out at a 180° Fahrenheit temperature. However, the temperature varies by company and model. 

Low-temp commercial dishwashers usually have washing and rinsing temperatures of 120° Fahrenheit and 140° Fahrenheit, respectively. 

5 Major Reasons Dishwasher Stops Drying Dishes

The dishwasher might malfunction for a variety of reasons. The following are four probable causes:

Heating Element

One of the most common issues a commercial dishwasher encounters when it does not dry dishes properly is a fault in the heating element. So, the first step is to inspect the heating element of a dishwasher. 

Testing of the Heating Element

To test the heating element, you must turn off the dishwasher and remove the heating element from the dishwasher's bottom. To do so, you must detach wires connected to the terminals on the heating element. 

Make use of a multimeter for a continuity test. Connect both probes to both terminals of the heating element. If the multimeter shows readings (you can check readings on the dishwasher's user manual), then the heating element is not defective. The heating element must be replaced if the continuity test does not yield any readings. 

Note: Before running continuity tests, set the multimer to the lowest resistance range. 

Vent Assembly

Many dishwashers use a vent assembly with a motorized door to let out hot steamy air generated during the rinse cycle. If the vent fails to open all the way, the moisture can remain on the dishes. 

Check the vent assembly to see if it is blocked or a problem with the motor. If the vent is blocked, then you should open it. In the case of the damaged vent, you must replace it. 

Vent Fan Motor

Most commercial dishwashers use a vent fan motor to blow the heated air out of the vent as soon as the rinse cycle is finished. If the fan blades are damaged or the motor itself is defective, the dishes cannot be appropriately dried.

Like the heating element, you can continuously test the vent fan motor using a multimeter. If it shows no readings, you'll need to replace it.  

Note: Before running continuity tests, set the multimer to the lowest resistance range. 

Thermostat

Dishwashers come up with high-limit thermostats, which act as safety switches to save them from overheating. If a thermostat malfunctioned, it would turn off the dishwasher, and the dishes would not get dry. If you receive a complaint about a dishwasher that is not drying dishes, you should test a thermostat. 

Testing of the Thermostat

  • The first step is to turn off the dishwasher by unplugging it. 
  • Take out the thermostat, which is usually on the bottom of the dishwasher. 
  • Conduct a continuity test on the thermostat by connecting probes of a multimer with the thermostat terminals. 
  • At room temperature, if the multimeter shows the readings, the thermostat is not faulty. 
  • Now, take the thermostat closer to the heater/lamp and see if the thermometer reads 0 reading. Otherwise, the thermostat must be replaced. 

Note: Before running continuity tests, set the multimer to the lowest resistance range. 

The issue in a Rinse Aid Dispenser

Another major issue that may cause a dishwasher to stop drying dishes is a defective Rinse Aid dispenser. If a Rinse Aid dispenser is not present in a dishwasher and is faulty, dishes will not properly get rid of moisture.

Unplug the dishwasher and take off the cap from the inside of the dishwasher door. Check for the existence or absence of a rinse aid dispenser. If the dispenser is not present, you should introduce it into the dishwasher. In the case of a damaged dispenser, you must replace it to ensure the proper functioning of the dishwasher.