Hotpoint Dishwasher Sanitize Light Not Working:... | appliancefaults.com

Technical Background:

The sanitize light on a Hotpoint dishwasher is typically controlled by the Main Control Unit (MCU). The MCU monitors the water temperature during the final rinse cycle. If the water reaches a specific temperature (usually around 150-160°F) and is maintained for a specific duration, the MCU then activates the sanitize light via a low-voltage signal. Failure of the light to illuminate can be due to issues with the heating element, temperature sensor (thermistor), the MCU itself, or the wiring between these components.

Symptoms:

The homeowner reports that their Hotpoint dishwasher completes its cycle, dishes appear clean, but the sanitize light does not illuminate at the end, indicating the sanitization process may not have occurred.

Possible Causes:

Heating element failure: The water isn't reaching the required temperature for sanitization.
Thermistor malfunction: The thermistor isn't accurately reading the water temperature, preventing the MCU from activating the sanitize function.
MCU failure: The MCU isn't processing the temperature data correctly or sending the signal to activate the light.
Wiring issue: A break or loose connection in the wiring between the heating element, thermistor, and MCU.
Insufficient water fill: Low water level prevents proper heating to sanitation temperatures.
High limit thermostat tripped: Prevents heater from energizing.

Solution:

1

Disconnect power to the dishwasher at the breaker panel (LOTO procedure required).
2

Using a multimeter, check the resistance of the heating element. A typical reading should be around 10-30 ohms. An open circuit indicates a faulty heating element.
3

Inspect the thermistor. Its resistance should vary with temperature. Consult the service manual for the specific resistance range at room temperature (approx. 77°F).
4

Check the wiring harness connecting the heating element, thermistor, and MCU for any signs of damage or loose connections. Use a wiring diagram to trace each wire.
5

Verify the voltage to the heating element during the heat cycle using a multimeter. You should measure approximately 120V AC. If no voltage is present, check the high-limit thermostat for continuity.
6

If the heating element and wiring check out, the MCU may be faulty. Replacement of the MCU may be necessary, but consider consulting the service manual for any diagnostic codes or self-test procedures before replacing.
7

Reconnect power and run a test cycle to confirm the sanitize light is functioning correctly.

Safety Warning:

Always disconnect power to the dishwasher at the breaker panel before performing any repairs. Use proper Lock-Out/Tag-Out (LOTO) procedures. Some components may retain a high-voltage charge even after the power is disconnected.

Prevention:

• Run the dishwasher regularly to prevent components from seizing up.

• Use a dishwasher cleaner monthly to remove mineral deposits that can affect heating element performance.

• Inspect the spray arms regularly for clogs.

Expert Tip:

Many Hotpoint dishwashers have a service mode that can be accessed by pressing a specific sequence of buttons (e.g., High Temp Wash - Heated Dry - High Temp Wash - Heated Dry). This mode can display error codes and allow you to run diagnostic tests.

Follow-up Questions:

Frequently Asked Questions

•What is the exact resistance range I should expect from the thermistor at room temperature?

Refer to the specific service manual for your Hotpoint dishwasher model. However, a common range is between 5k and 15k ohms at 77°F. The resistance decreases as the temperature increases.

•Where is the MCU located in my Hotpoint dishwasher?

The MCU is typically located behind the control panel, either on the door or at the top of the dishwasher. You may need to remove the outer door panel to access it.

•How do I know if the high-limit thermostat is tripped and where is it located?

Use a multimeter to check for continuity across the thermostat terminals. If there's no continuity, it's tripped. The high-limit thermostat is usually located near the heating element housing, often clipped directly to the heater assembly.

Hotpoint Dishwasher Sanitize Light Not Working: Troubleshooting Guide

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What is the exact resistance range I should expect from the thermistor at room temperature?

•Where is the MCU located in my Hotpoint dishwasher?

•How do I know if the high-limit thermostat is tripped and where is it located?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: