Before troubleshooting electrical circuits, the technician needs to learn to first visually check the obvious conditions. This includes inspecting the thermostat to verify if it is on and adjusted to trigger the circuit. Next, the technician can check circuit breakers and disconnects. If all appears usual, the control panel should be opened to check the equipment and fuses.
When it becomes time to check the electrical circuit using the diagram, troubleshooting can be easier if the technician simplifies the circuit to three major areas:
- Line voltage
- Low voltage
- Thermostat control
This means to first locate on the schematic the thermostat circuit and analyze it. It is the primary control and without it nothing else will work. Using the voltmeter will immediately determine if the control circuit is sending a signal to the unit. Next, check the line voltage side of the transformer and the secondary side of the transformer for control voltage. If all appears normal as expected, then begin to jump through the circuit looking for open switches or failed components. Remember, an open switch will read potential voltage difference and a closed switch will not.
Good preventative maintenance while working on electrical controls includes inspecting for loose wiring, work connections, and dirty or pitted contacts. Wiring and connections should be repaired, but contacts which are pitted should be replaced. Occasionally, a dirty contact can be cleaned with an industrial-grade contact solvent, but this is often only a temporary fix to keep the equipment running.
Whether you live in Loudoun County, Fairfax County or Manassas, HVAC inspections and electrical testings must be done regularly.
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