Advanced Troubleshooting Section

The advanced troubleshooting section allows you to diagnose equipment problems by measuring all major operating parameters. High and low side refrigeration gauges display operating pressures. A digital temperature meter allows measurement of refrigerant and air temperatures in several key locations. PT charts are provided for the refrigerant being utilized. Electrical measurements can be taken at any of the test points on the electrical schematic. This is your opportunity to apply all of the theory and diagnostic techniques taught in this e-book and troubleshoot problems with realistically portrayed equipment faults. Below is a screen shot of the advanced troubleshooting user interface. The key features are indicated with circled red numbers. The features are explained in detail below the screen shot.

The title informs you which equipment type and refrigerant you will be diagnosing. You must know whether the system is a high, medium or low temperature application so that you can come to conclusions about operating pressures and temperatures.
The Help Button opens this help page in a new window.
The Hint Button provides clues such as might be given by the equipment owner.
The PT Chart Button opens a new window containing the PT Chart relevant to the equipment being diagnosed.
The Abbreviations Button opens a new window which lists the meanings of the abbreviations in the Notes section (13)
When you believe that you have correctly diagnosed the problem click the Submit Diagnosis button to open a new window where you may submit your diagnosis and find out if you are correct.
The low side and high side pressure gauges can be activated by clicking the small Buttons labeled P1, P2 and P3. Each Button corresponds to identically named test points on the refrigeration piping diagram (8). Note that when you click one of the buttons it turns green and the corresponding test point on the piping diagram also turns green.
The piping layout also contains temperature test points which are labeled T1, T2, T3…etc. It also contains pressure test points which are labeled P1. P2 and P3. Test points turn green when activated by the corresponding test instrument. (gauges or temperature meter)
The electrical schematic operates exactly like the diagrams you have already experienced in the previous troubleshooting sections. The test points turn green when activated by the Volt/Ohm/Amp meter.
The Volt/Ohm/Amp meter operates exactly as in the previous troubleshooting sections. The mode buttons turn green when clicked to indicate the test mode.
The digital temperature meter has 9 buttons which correspond to the 9 temperature test points on the piping diagram. When you select a button it changes to green and the corresponding test point on the piping diagram also changes to green providing a helpful visual reference.
The unit nameplate provides electrical ratings for the equipment components.
Click the Abbreviation Button (5) to see the meaning of the abbreviations listed in the Notes section. The Notes section allows you to record pertinent information as you gather it. For example, when determining superheat, it is helpful to have a handy place to record data such as low side pressure (LO), suction line temperature (SLT) and the corresponding PT Chart temperature (CORR). Each time you gather more data about the operating parameters record it in the Notes section. You may not need to fill it in completely to make a diagnosis. On the other hand, the more information you gather, the greater is the likelihood that your diagnosis will be correct.

Electrical Measurements
Amps When the meter is in amps mode and you click a test point, the amperage draw of all the loads in that electrical branch are displayed in the meter. If there are "sub branches" those loads are included.
Volts When the meter is placed in the voltage mode one test point is automatically selected. This is typically either the the Common leg or Line 2. You must select the 2nd test point. The volt meter then displays the voltage potential between those 2 points. A volt meter reports a voltage potential across an open circuit and across loads.
Ohms The power in an electrical circuit must be turned off before using an ohm meter. If you fail to do so you may damage the ohm meter or at least blow the meter's fuse. Anytime you put the meter into ohms mode it is assumed that the power has been turned off. To measure the resistance of a component select the 2 closest test points. It is assumed that any parallel loads have been taken out of the circuit. If you try measuring a circuit with several loads in parallel or series you are likely to receive the following alert:
  In real life you will have an ohm reading representing the combination of all the series and/or parallel resistances between the 2 test points you selected. However those types of readings are seldom useful when troubleshooting. That is why you must isolate components from the rest of the circuitry to take a resistance measurement. You may still attempt any measurement you wish and are not restricted to adjacent test points only. When it is somewhat obvious that a specific component or wiring circuit is being tested you are likely to be given a reading. The further apart your test points are, the greater is the liklihood that you will receive the above alert instead of a meter reading.

When you take a reading that has direct continuity (zero resistance) between 2 test points and there also happens to be a measureable resistance in parallel, the measureable resistance load is ignored. This is true in real life as well as in these troubleshooting boards. That is because electricity will favour taking the route of least resistance.