Electrical Fundamentals

The Core Three: Voltage, Amperage, Resistance

To diagnose an electrical failure, you need to understand the relationship between three main concepts (Ohm's Law):

• Voltage (Volts - V): The "pressure" pushing the electricity through the wire. Most US appliances use 120V, while heavy heaters (dryers, ovens) use 240V.
• Amperage (Amps - A): The volume of electricity flowing. High amps generate heat (like a bake element).
• Resistance (Ohms - Ω): How much a component resists the flow of electricity. We measure Ohms to see if a part (like a sensor or heating element) is broken.

Using a Multimeter

Your digital multimeter is your best friend. The most common test in appliance repair is the Continuity Test.

• What is continuity? It means there is a continuous, unbroken electrical path through a component.
• How to test: Set your multimeter to the continuity setting (often looks like a Wi-Fi or sound symbol). Touch the two probes together—if it beeps, your meter works. Next, touch the probes to the two terminals of the unplugged component (like a thermal fuse). If it beeps, the part is good. If there is no sound and the screen shows 'OL' (Open Loop), the part is blown and needs replacing.

Common Electrical Components

You will frequently encounter these parts when taking appliances apart:

• Thermal Fuses: Safety devices that blow when it gets too hot. They must have continuity. If blown, they must be replaced, not bypassed.
• Thermistors: Temperature sensors that change resistance based on temperature. You test these by measuring Ohms and comparing them to a tech sheet at specific temperatures.
• Solenoid Valves: Electromechanical valves (like water inlet valves). You test the coils for resistance.
• Switches: Door switches, lid switches. They mechanically open and close circuits. You test them for continuity while pressing the switch button.