Saturday, June 8, 2013

Random Puzzle Assembly

Many students trying to troubleshoot HVACR systems have difficulty navigating the sheer amount of data one can collect. If you go about just collecting a lot of data, it does not take very long to confuse yourself. I often see people taking resistance, voltage, and current readings on just about every conceivable location on the system without having a clear idea why they are taking the readings. This is like trying to build a 1000 piece jigsaw puzzle by just randomly trying to fit pieces together without looking at the shapes or color patterns on the pieces. When building puzzles, it helps to have a plan. There are different plans – outside edges first, organizing pieces by color, or organizing pieces by shape, but having a plan improves your chances of success. Troubleshooting is the same way. You should have a plan to organize your data collection into something meaningful. You should know why you are taking a voltage, resistance, or current reading before taking the reading. Ideally, each measurement you make should eliminate an area of inquiry. A simple example is checking the power supply to the unit. If you read the correct incoming voltage, you can eliminate that as a source of the problem. But if you don’t read the correct voltage at the power supply, then there is no need to check anything inside the unit until you have solved the power supply problem. There are probably as many systems as there are technicians. It is not too important what your system is, so long as it is based on an understanding of how the equipment functions and proceeds logically. For a non-functioning component, I generally want to know if that component is receiving the correct voltage. If it is, then I need to take a closer look at the component. Otherwise, I need to check the circuit that supplies voltage to the component. Many technicians check the line voltage and control voltage first. This does not take long and covers a large number of problems. Another technique is to start at the thermostat and work towards the non-functioning component until you find a break in the circuit, or eventually reach the component. The key point is that each piece of data you collect should tell you something. This will allow you to take far fewer readings and isolate the problem much faster.

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