3hp Blower Motor Replacement
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Before Eric went to work on the motor, it had burned out, was replaced, and burned out again. He also notices insect nests in the panel, the contactor in the supply airstream, a missing keyway, and an oversized breaker, which are all less than ideal.
The pulley also cannot spin and is in poor shape overall. Eric attempts to remove the pulley with a two-jaw puller, but the task proves difficult; the motor shaft doesn’t spin at all. Since the pulley has suffered so much damage, Eric replaces it entirely.
Eric disassembles the contactor, which has been warped from the motor burnout. That contactor tripped the 60-amp breaker.
Eric wires the motor for the 208-230v application. The high-voltage wires go to the motor starter and feed into the top, and the wires go down into a new 20-amp breaker. All of the wires are #12 wires. Additionally, the motor starter has a high-voltage coil, and a relay pulls in the starter. If the overload relay were to change state, it would stop the motor. The wiring is configured so that the compressor will not run if the contactor is not pulled in; this is a common practice in commercial equipment .
The high-voltage wiring joins with the low-voltage wiring in the junction box. Eric ties in the condenser to the thermostat (white), float switch (breaking red), 600v rated wire to starter enclosure (green or yellow), and common (blue) wires. He labels everything to keep track of all of the controls.
When Eric runs the blower, he checks the amperage at the control box. He discovers that the white wire gives the cooling signal to the condenser, so he decides to switch it with the yellow wire at the box. He also draws a schematic, fixes any bent components, and seals up the conduit and all the holes he finds to prevent moisture from getting into any of the electrical components.
Before walking away from the job, Eric also adjusts his relay and tests it to see if it stops the unit when it’s supposed to.
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