Susan Brown

[Susan Brown]

Can you tell me which video and the time stamp where we discuss this?

[Susan Brown]

Hi Nate,

It looks like you already retook this quiz and got everything correct except #5.

Question #5: At what locations in this diagram would you make the test that you indicated above?

Answer: The explanation says “You’re checking to see if the noise filter is capable of putting out 120 V AC. Looking at the schematic, the output is at the points labelled L2 to N2.”

So I would test from L1 to L2?

The correct answer is given in the explanation – L2 to N2. If that doesn’t make sense, let me know and I’ll get more help for you!

[Susan Brown]

Hi Nate,

The timing chart tells you which timer switches are closed for the cycle and load of interest. You will then use that information on the schematic (which switches are open or closed) to trace out Line and N for the load of interest (in this case, the pump). The closed switches determine the paths.

Here’s an image that might help you to understand which contacts are where.

T17 is only present up to the switch node I circled and labeled T17. Same thing for T18. T16 comes up to the node labeled T16. If you look at the whole schematic again, you’ll then see that it goes down to Cam 8. With that in mind, hopefully you’ll understand why Scott drew the neutral line the way he did, based on the timing chart saying Cam 10 would connect 16 to 17, and Cam 8 would connect 13 to 16. Does that help?

[Susan Brown]

You’re welcome!

[Susan Brown]

Yes, you are allowed to do that, although it is good to push yourself to try to first answer a question from memory. But if you are stumped, looking at the course material during a quiz is fine. We’d rather you do that than simply guess at the answer!

If you do that, be sure you don’t navigate away from a quiz once you’ve started it. If you need to look in a different unit than the one the quiz is on, open it in a new tab or window.

Thanks for asking!

[Susan Brown]

Hi Art,

I’m not sure what you mean about getting the answer correct but not getting credit for it. I’ll send you an email – that’ll be an easier way to get this straightened out.

By the way, we encourage students to get 100% on as many quizzes as possible. We are quizzing you on important things to know for your job, and we give you two attempts to figure out the correct answers. The more you figure out now, the more profitable you’ll be in your work!

[Susan Brown]

Hi there! I’m always glad to see students thinking these things through.

Yes, we suspect that we’ll measure OL, but anytime we do an electrical measurement we want to know what the spec is and compare the measurements to that. The spec is what we expect. It’s a fine point, particularly in this scenario, but we like to have a consistent approach when it comes to interpreting measurements.

[Susan Brown]

Great job, Nate – you’ve got it right for both of those. The only other thing I like to see mentioned for Question 9 (just to really nail down the details) is what do those measurements also mean in terms of current flow for the circuit?

[Susan Brown]

I’m really baffled by why you want to argue about this so much. You also don’t seem to be reading my replies carefully.

No- the first systems you checked were
1. the air distribution system (“not hearing the evap fan motor”)
2. the refrigeration system (“put ear against fridge to listen for any humming”)

In the quote above, I was summarizing what you did in your example scenario. Pointing out that you did not in fact check the controls first, as you were saying that a tech should do before the refrigeration system. This was meant to show that what you and I are saying is not all that far apart.

I then went on to point out that:

BTW – it is fine to note whether or not the evap fan is running while you are shooting the compartment temperatures to verify the complaint, but it is a very weak piece of information – you can’t really do anything diagnostically with that at this point if both compartments are indeed warm.

I don’t know how you read any of this as an endorsement of starting your troubleshooting of a warm freezer/fridge at the air distribution system. I have consistently been saying that the compressor is the first thing you want to know about.

[Susan Brown]

I think you are reading things in our statements that are not there, which is why you think there’s a big disagreement here.

You already told us that you yourself first listen for the compressor (which is part of the refrigeration system) before tapping the cold control (which only works on a small group of refrigerators, by the way). If you heard the compressor running, you wouldn’t bother to tap the cold control, right?

A tech’s first check on a warm box should be to see if the compressor is running – period.

And that is what we mean by checking the refrigeration system first.

before bothering to test if all the refrigeration system components are operating.

We have not said that you’ll check each and every component in the system before turning your attention to the other systems, no matter what you find.

For example, on a warm freezer/ff compartment complaint, if the compressor is not running, then we would not proceed to check the rest of the sealed system. Instead we would then turn to the control system.

Thinking in terms of systems helps techs approach all of the refrigerator models out there, even newer ones, in a logical and efficient way. You want your troubleshooting to be systematic, not idiosyncratic, and grounded in a fundamental knowledge of how the systems work with each other in the appliance. Knowing model-specific tricks like tapping on a cold control is icing on the cake – but it is not the cake itself. And I think if you carefully compare what we are saying to what you actually do on a service call, you’ll see a lot of agreement.

[Susan Brown]

My way: I open up freezer door, not hearing the evap fan motor, i close door, put ear against fridge to listen for any humming. When i dont hear any humming, i tap on cold control, and fridge kicks to life. First system i checked was the temperature control system

No- the first systems you checked were
1. the air distribution system (“not hearing the evap fan motor”)
2. the refrigeration system (“put ear against fridge to listen for any humming”)

THEN you checked the control system because you didn’t hear any humming. If you had heard the compressor running, you would have known to investigate the refrigeration system further.

You checked the compressor before the controls, which is exactly what we teach.

BTW – it is fine to note whether or not the evap fan is running while you are shooting the compartment temperatures to verify the complaint, but it is a very weak piece of information – you can’t really do anything diagnostically with that at this point if both compartments are indeed warm.

Remember, we’re teaching a troubleshooting system – a way of organizing our thinking and approach to troubleshooting all types of refrigerators – split-phase, BLDC, linear compressors, as well as single and dual-evap, with all kinds of control schemes. Of course techs will develop a few additional techniques or modifications based on particular models as they gain experience. For example, you’ll know that certain types of compressors will be impossible to hear by putting your ear against the fridge (e.g., BLDC, linear). But those are just layers that you add on top of a foundation of solid, logical thinking.

[Susan Brown]

No problem! It’s easy to hide answers, and I like students to see that others are using the Forums to get personalized help. Some students avoid asking questions for some reason, even though they obviously need to!

[Susan Brown]

Hi Nate – that is correct! I’m going to hide the answer, FYI, so we’re not giving away too much to other students.

[Susan Brown]

What I mean is that checking to see if the compressor is running, doesnt tell me if it SHOULD be running.

If both compartments are warm, then of course the compressor should be running! 🙂

Listening for evap fan noise is sometimes a good move but not diagnostically conclusive in the case where both compartments are warm.

The only diagnostically conclusive move at this point is to determine if the compressor is running or not. This also half splits the problem between the compressor and the other three systems.

We’re just talking about listening, depending on the type of compressor. Or, you may need to roll out the fridge and get a closer look/feel.

We teach a logical approach to troubleshooting that follows a carefully thought out rationale to maximize diagnostic information with minimal disassembly. But, are there other ways to get to the correct conclusion? Of course, but they won’t be as efficient. We like to do more work with our brains and less with our hands!

BTW – I encourage you to be more specific in your terminology. Saying that the “refrigerator should be running” is not precise. The refrigerator is the entire box with 4 systems.

[Susan Brown]

Hi Nate – I’m going to email you about this.

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