Components

Run Capacitor

What a run capacitor actually does for a motor, and how to tell when it has failed.

Components

Contactor

The low voltage controlled switch that connects line voltage to the outdoor unit.

Components

Start Capacitor and Hard Start Kit

What a start capacitor does during the first moments of a motor start, and when a hard start kit is appropriate.

Components

Relay

A low current coil switching a higher current load, and the relay types you meet in HVAC controls.

Components

Control Transformer

The component that creates the 24 volt control circuit, how it is sized, and why its fuse keeps blowing.

Components

Sequencer

The time delay device that staggers electric heat elements so they do not all energize at once.

Components

Pressure Switch

Safety switches that prove draft or protect a refrigerant circuit, and how to read what an open switch is telling you.

Components

Limit and Rollout Switches

Temperature safeties that shut down heating equipment, and what each one is actually reporting.

Components

PSC Motor

The permanent split capacitor motor used in many blowers and condenser fans, and how it behaves as duct resistance rises.

Components

ECM Motor

Electronically commutated motors, the difference between constant torque and constant airflow, and how to troubleshoot them.

Components

Hermetic Compressor

The pump at the heart of the refrigeration circuit, common types, and how to evaluate one before condemning it.

Components

Reversing Valve

The four way valve that lets a heat pump swap the roles of the indoor and outdoor coils.

Components

Metering Devices

Fixed orifice, thermostatic expansion valve and electronic expansion valve, and how each controls the evaporator.

Components

Circulator Pump

The pump that moves water through a hydronic loop, how it is sized, and why head matters more than pressure.

Components

Expansion Tank

Why a closed hydronic loop needs room for water to expand, and how to check a diaphragm tank.

Components

Zone Valve and Zoning

How zoning delivers heat only where it is called for, using valves or multiple circulators.

Components

Thermostats and Control Wiring

What each control wire does, how thermostat types differ, and how to troubleshoot a control circuit.

Components