Everyday Scope Use – It’ll Do More Than You Think
Instructor Peter Meier - - Motorage Technical Editor
“Let’s paint a picture,” Instructor Meier starts the class with, referring to the scope display on the screen, “Let’s look at the entire forest and not just the trees,” he went onto say. That started the class thinking, thinking there must be some great secret to scope reading that this instructor knows. They were all on the edge of their seats waiting for that “big” secret to be revealed. The problem is… there is no secret, there is no magic to it, all it takes is a few hours with Instructor Pete Meier to find out just how easy and versatile using a scope can be. Instructor Meier is no stranger to the end of wrench or using a probe to evaluate a vehicle’s problems. He’s a former technician himself with years and years of experience behind him. Pete will tell you himself, “I’m not the smartest guy out there. I’m just passing on what I’ve been taught.” Modest, yes, but from my viewpoint I think this guy is pretty sharp, and with his down to earth teaching method that he uses I don’t feel intimidated trying out the methods he describes in his class. I’m no stranger to using a scope myself, but I sure can learn more, and every time I attend one of Pete’s classes I come away with a bit more knowledge and confidence in using a scope than I had before. Instructor Meier covered not only simple positive and negative signal readings but also amperage clamp and pressure transducer usage. Voltage drop was another hot topic that got a lot of the class eager for more information. Cylinder pressure testing, timing belt checks, vacuum, injector signals, and cam to crank signals were also covered. Pete covered basic theory and scope screen interpretation too. It might be something a seasoned technician that uses a scope everyday wouldn’t think was all that important to go over, but for the novice scope user this was very important and Instructor Meier took the time to explain it all in detail for them. Pete told the well-attended class, “Scope reading gets easier the more you do it. Practice using a scope on a known good circuit and the more you practice the more likely you’ll use it to speed up your diagnostic time and know what to look for on the vehicle with a problem.” With lots of different scope patterns, and lots of discussion between the instructor and class attendees this was by far one of the best classes to attend at this year’s MACS convention. It was certainly the one class that you could ask a question to the instructor but the instructor wasn’t going to just give you the answer. The two of you discussed it so that you not only figured it out yourself, but you understood the theory behind it. A top rate class and one I’m glad I didn’t miss.
Inputs, Outputs and Interior Comfort Controls
“Why are there so many changes in the HVAC systems of today’s cars?” Instructor Jerry Mungle said to the class, “One word says it all – efficiency.” With the government regulations for fuel economy today’s cars have to be more efficient than their counter parts from just a few years ago. This class put all of those regulations and requirements into perspective as to how it’s being achieved. From new thinner oils, smaller compressors, computer software, and a whole lot more. “It’s all in the communication” was Instructor Mungle’s catch phrase for the class, and how true it is. The communication between computer modules, interior and exterior conditions as well as the driver’s initial commands were all part of his presentation. He also explained the changes to the variable compressor from the original spring and diaphragm type to the duty cycle controlled electronic solenoid type. Performance codes were another hot topic that got a lot of response from the packed room of attendees.
There was even a little time left to go over clutchless compressors, electrical compressors and stretch belt technology. Instructor Mungle chuckled a bit while explaining how the term “stretch” is really misleading. As he said to the group, “I don’t know how the term stretch became the norm. They actually “shrink” to fit. These belts are designed to have just enough clearance to install them. Friction causes the belt to actually shrink to the engineered size that will provide the correct tension on the pulleys. If they stretched wouldn’t it just fall off? Think about it.”
Serial data information was another hot topic. He said to the group, “Communication and the number of data lines are only going to increase in the future, which may not be for adding more components but more features. With the various data lines in use today such as the high speed lines, local lines, and low speed the possibilities are endless as to what can be accomplished.” And if learning more about the data information side of the HVAC systems wasn’t enough Instructor Mungle brought the class up to speed with the ever growing changes in core sizes and the types of HVAC controls that the technician will be facing. Integrated Center Stack (ICS), Human Machine Interface Controls (HMIC) are just a few of the new innovative processors/controls that Jerry talked about.
There was a lot of discussion on engine idle and compressor engagement, interior air quality, placement of certain interior/exterior sensors, and the ability to control interior air quality. A good example brought up by Instructor Mungle was if someone was smoking in the car and cracked the d.side window just a bit. This subtle change affects the interior air not so much because of the smoke but because of the air temperature from the outside that changes the interior air readings. You’re so right Jerry; it truly is all about the communication. One class that I’m glad I didn’t miss at this year’s MACS convention.
“It Ain’t That Hard”
Was the opening statement Instructor Richard Sheffield, ASE CMAT, L1, X1 and SAE member started his class with on “New Perspectives on HVAC Diagnostics”. Instructor Sheffield’s long automotive career began back in the 70’s and is currently a shop owner as well as one the leading instructors in the business. One of the main points he stressed to the overflowing classroom was not to fall into the old trap of thinking; “I have always done it this way. Only to find out later that something has changed. Changes in procedures are part of the evolution of the automobile, but the physics and thermal aspects of HVAC remain the same.”
Richard went on to show the relationship between understanding the terminology, scope readings, and scanner results to arrive at a solution. Many times he referenced to the so called, “Calibrated Hand” that we all are guilty of using to test the quality of either the vent temperature or the amount of air flow out of the vents. As he stated, “This might have worked back in the day, but with today’s systems even having the hood up can affect the air conditioning pressures, quality of interior air, and the results of your diagnosis.”
The class covered TXV, accumulators, driers, blower motors, orifice tubes, and every other components involved in the HVAC system. Some of the highlights of the class came from the abundance of class participation. Questions were asked and discussed with an in-depth study as a group on how to best tackle that particular problem. This was somewhat different than any other classes that I have attended, and I must say, very affective. Richard made it a point to get everyone in the class involved. (Nice touch Richard)
“Know your tools,” Instructor Sheffield told the group, “Developing an understanding of what you are seeing on the scope vs. what the customer is experiencing is all part of the diagnostic procedure.” The science of the A/C systems is where the diagnostics actually starts according to Sheffield. His approach to diagnosing an HVAC system is all about knowledge. “Create an understanding of the physics, the terms, the tools, and the techniques involved with the HVAC systems,” Richard told the class, “With that in hand, you can then better understand what is coming out of the vents.”
With several examples and scope readings on the screen the class got a firsthand look of how invaluable understanding the results of quality testing really can be. As Richard pointed out, “You just can’t do the same thing as we’ve done in the past. The new systems have higher tolerances. Years ago a few ounces off (oils or refrigerants) didn’t make that much of a difference. These days, it’s critical. Using the tools available today is no different than using the tools of yesterday, ya just have to learn how. As Richard said, “It ain’t that hard”.
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