10 components coveredField manual · Fundamentals
Component testing reference: what a good part reads (fuses, thermostats, sensors, coils, motors, switches, diodes)
Covers: Common electromechanical and simple electronic parts in US appliances; generic pass/fail logic and only those numeric ranges that 2+ independent sources agree on. Model-specific values come from the tech sheet
One page to answer 'is this reading good?' for the parts you test most. Where a number is broadly agreed (diode drop, capacitor tolerance band, closed contacts near 0 Ω) it is given; where values vary by model (coil, motor and sensor resistances), the method and the comparison logic are given instead. Always isolate the part from the circuit first.
Safety first
- Disconnect power and verify zero voltage before resistance tests
- Discharge capacitors before touching or measuring them
- Live tests on boards and relays are caution steps: CAT-rated meter, insulated probes, no jewelry
How it works
Resistance and continuity tests are done with power off and the part disconnected on at least one side, otherwise parallel paths through the board or other loads give false readings.
Three readings tell most of the story: near 0 Ω (closed contact or fuse), a stable value in the expected range (heater, coil, winding, sensor), or OL (open). Each part type has one of those as 'good' and the others as 'bad'.
Resistance alone does not prove a part works under load. A motor winding can read correct and still have shorted turns or a seized bearing; a relay coil can read good and the contacts can be burnt. Pair ohms with a voltage or current check under load when possible.
Leakage to ground is a separate test: measure each terminal to the metal frame or sheath. A standard meter catches dead shorts; a megohmmeter is needed to find weak insulation that trips GFCIs.
Components & tests
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Always confirm values against the tech sheet for the exact model.
- CPSC recalls search
- SaferProducts.gov recall and incident search
- Whirlpool Corporation recall information
- GE Appliances recalls
- Frigidaire recall information
- Water heater and boiler recall lookup (A. O. Smith / Lochinvar)
- EPA Section 608 technician certification types
- OSHA control of hazardous energy (lockout/tagout)
- CPSC carbon monoxide information center
OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Smooth glass electric cooktop built into a wooden counter by Max Vakhtbovych, Pexels License
