By Yvonne Aubert. wiring. Published at Tuesday, March 26th, 2019 - 02:06:16 AM.
The importance of understanding and using wiring diagrams to troubleshoot refrigeration systems cannot be overemphasized. Most system problems can be divided into two broad categories: electrical or mechanical. However, the majority of system problems are electrical. Mastering the use of wiring diagrams enables a technician to better troubleshoot the system electrically, which will facilitate troubleshooting the entire system with more accuracy and precision.
“How can we make sure the compressor is safe to start?” Tim asked. “We want to make sure that it is safe to apply power to the terminals,” Bob said. ”Use the Ohmmeter set on RX10K (10,000 Ohms). Second, fasten one lead to a good ground, scrape any scale or paint off the suction line, for example, and firmly hold the lead to the bare spot. Then, touch the other lead to one of the compressor terminals and record any reading. There should not be a reading. If there is a reading, the compressor has a ground circuit in the compressor. A circuit from the motor windings to ground. ”To illustrate how your meter works, you should be able to read a slight reading through your body if you hold one lead in each hand,” Bob continued.
Being able to efficiently interpret ladder (line) diagrams is an important part of electrically troubleshooting many HVACR systems. These diagrams are drawn in such a format that it is quite easy to understand the electrical configuration of the system. The ease in reading these diagrams is accomplished by drawing each load and any switches that control that load on a separate horizontal line. For example, if a load is not energized when it should, a technician should be able to easily identify which switch or switches control that load and then start to troubleshoot the cause. Ladder diagrams are also drawn with other helpful identifiers to aid a technician in electrically troubleshooting a system.
One time I had a buddy with 90 “defective” boilers; this was the guy who forgot to check the gas meters. The next time he called me he had 265 defective boilers. Of course, my first question was, “Do you have gas?” After I got called some nasty names, we proceeded with the questioning. I asked him if he had 110 V to terminal L1 and L2. This is always our starting point, making sure the electricity is turned on. I got the classic answer: “How do I know, I’m only a plumber.” I asked to speak to the electrician, who confirmed that he had power to L1 and L2. I asked what the voltage was; sometimes you have lower voltage and the system won’t work. He confirmed that he had 120 V. Next, I asked him if he had continuity through the control circuit. His answer was, “I’m a union electrician, I put power to the boiler and hook up thermostats; I don’t know about boiler wiring.” It was time for a field visit.
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