1. TEST METER OPERATION

2. Electrical Test Instruments Analog Or Digital Voltmeters – Measuring Potential Difference Ammeters – Measuring Current Flow – Clamp On Ohmmeters – Measuring Resistance And Checking Continuity Capacitance – Check Capacitors Multimeters – VOM/DMM - All The Above

3. Troubleshooting Need proper meters to do proper diagnostics –Multi meter –Amprobe

4. General Awareness Job Site Safety Lock-Out/Tag-Out Personal Safety Clothing Lifting Fire Pressure Hazardous Materials Service Trucks Electrical First Line Of Safety Trust Your Sixth Sense And When It Tells You Not To Do Something DON’T DO IT!!!

5. DIGITAL MULTI-METER CLAMP ON AMP PROBE

6. VOLT/OHM METER OPERATION

7. CHECK FOR AN OPEN CIRCUIT A break in the continuous path of an electrical circuit. 1. Indicated by an infinity reading with an OHMMETER. 2. Indicated by a voltage reading with a VOLT METER.

8. CHECK FOR A SHORT CIRCUIT When the electrons take a path back to the source that allows its to bypass all or most of the circuit resistance. 1. Indicated by a blown fuse – read VOLTAGE across the fuse. 2. Indicated by reading INFINITE OHM across fuse. 3. Indicated by a ground (When electrons take a path back to the source that adds additional resistance to the circuit) ZERO OHMS READING at component being checked to ground.

9. L1 to N & L1 to G = Same; +/- 2 volts N to G = 0 L1 & N= V L1 & G= V N & G= V USING A VOLT METER TO CHECK FOR POWER AND POLARITY

10. VOLT METER CHECK FOR ELECTROMOTIVE FORCE – EMF (POWER)

11. Check for Open and closed switches Load 120 VOLTS 0 Load 120 vac Pitting will cause a voltage drop across a set of closed contacts.

12. ELECTRICAL INDICATING DEVICES Voltmeter Always used in parallel with the load or the switch to be tested. N H 120 v MOTOR Voltmeter Emerge ncy Switch 0 120

13. Voltage Drop When checking the voltage applied to a load such as an outdoor unit, the voltage applied should be measured in two steps: first with the load de-energized and then with the load energized The difference between the de-energized and the energized voltage is referred to as the voltage drop

14. Voltage Drop The voltage should not drop more than 3% of the de-energized applied voltage A voltage drop higher than 3% usually indicates that the gauge of the wire leading to the load is too small For example, if 223 volts were measured at the contactor of the outdoor unit de-energized…

15. Voltage Drop And then 220 volts were measured with the contactor energized… This would indicate a voltage drop of only 1.35% This would be an acceptable voltage drop

16. Voltage Drop However, if 223 volts were measured at the contactor of the outdoor unit de-energized, and then 210 volts were measured with the contactor energized The voltage drop would be: This would be an unacceptable voltage drop 223 – 210 X 100 = 5.82% 223

17. Troubleshooting Switches Switches that are closed will have no voltage drop Switches that are open will have line voltage across their terminals Switches are wired in series with loads and are used to control their operation, such as a low pressure switch

18. Ohm Meter Measures Ohms or Resistance

19. Load OHM Load 0 OHM Digital Meter: OL Digital Meter: 0 120 vac Pitting will cause a reduced ohm reading across a set of closed contacts. ∞

20. N S ∞ 0 Batteries Zero adjustment C S R Ω Com Analog scale Permanent magnet Iron core (bobbin) Coil Compressor terminals 100 500 10 Never connect an Ohmmeter to an energized circuit

21. Ohmmeter Always disconnect power to the circuit being tested first. Then use the Ohmmeter in parallel with the load or the switch to be tested. Ohmmeter 120 v N H MOTOR Emergency Switch

22. Ammeter Measures Amps or Current Flow

23. Load AMP 0 120 vac Load AMP 6 120 vac

24. Ammeter Always used in series with the load or the circuit to be tested. Ammeter MOTOR 120 v N H Clamp-on ammeter Alternative method is to use a clamp- on ammeter. Emergency Switch 6

25. Thank you for your time and attention