Capacitors, contactors, relays, thermostats, motors and diagnostic procedures.
40 cards · basic cards · AI-written, checked twice. Edit anything.
- What is the primary function of a capacitor in an HVAC system?
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Provides voltage boost and phase shift to motor winding- What unit of measurement is used for capacitor capacity?
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Microfarads (uF)- What is the main difference between a run capacitor and a start capacitor?
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Start capacitor has higher capacity and is in circuit briefly; run capacitor stays in circuit- What does a failed capacitor typically look like when opened?
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Bulged, exploded, or vented casing- Why must a capacitor be discharged before touching it?
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Stores electrical charge that can cause shock or damage- What voltage rating should match when replacing a capacitor?
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Must match or exceed the system voltage on the nameplate- How do you safely discharge a capacitor?
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Short the terminals together with an insulated screwdriver- What is the purpose of a contactor in HVAC?
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Switches high-current circuits on/off via a low-voltage control signal- What activates the coil of a contactor?
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Low voltage signal from thermostat or control board- What symptom indicates a contactor is chattering?
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Rapid clicking or buzzing sound from the contactor- How many amperes typically flow through a contactor coil?
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Low current, usually under 1 ampere- What test checks if contactor contacts are making good electrical connection?
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Continuity test with multimeter- What voltage appears across the contacts of an open contactor?
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Full system voltage, typically 240V or 480V- How does a relay differ from a contactor?
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Relay switches lower currents; contactor switches higher currents- What voltage is typical for a relay coil?
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24 volts
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