Sam Brown

[Sam Brown]

You got it! Your reading of the schematic is absolutely spot-on.

[Sam Brown]

Remember that, in order for the reignition system to detect that a flame is established, current has to return to the board through the chassis of the appliance. If there is a buildup of grease, char, or other crud, that can act as an insulator and interrupt the return path. When we’re talking about a burner, think about where you might find built-up debris that could cause this issue.

Hopefully that makes sense. If you’re still uncertain, you may want to review the video in module 7, unit 3.

[Sam Brown]

Apologies for the late reply — looks like my response from a couple days ago didn’t post.

To understand what the correct answers are (there are two of them), you need to understand the difference between an early-stage leak and a fully progressed leak. While a fully progressed leak will manifest differently depending on if it’s a low-side or high-side leak, an early stage leak manifests the exact same way as an undercharge.

This makes intuitive sense if you think about it — in the early stages, refrigerant has been lost through the leak, and therefore you do have an undercharge of refrigerant in the system. It’s this undercharge that causes the ice ball, since the below-spec charge of refrigerant in the system all flashes to vapor toward the beginning of the evaporator coil, creating the ice ball.

Does that all make sense? Do you know what the two correct answers are now?

[Sam Brown]

If you look at the diagram at around 7:00 in the first video, you’ll see that when both evaporators are being run in series, a lot of the refrigerant has already turned to vapor by the time it gets to the freezer evaporator. Less refrigerant to boil means less cooling. So while you might get some cooling at the freezer evaporator in this configuration, it won’t be the “normal” amount.

This is why, in the other 3-way valve position, it just sends refrigerant to the freezer evaporator. That is necessary to keep the freezer properly cold.

[Sam Brown]

it was a very low temp so I figured “subcooled” but how do I find the answer. Sub cooled wasn’t it.

What’s tripping you up is that you’re thinking of subcooling and superheat in terms of “really cold” and “really hot”. That’s not what they mean.

A substance is subcooled if is cooler than the saturation temperature for its current pressure. Similarly, it’s superheated if it’s hotter than the saturation temperature.

So all you have to do is look at that temperature you’re measuring, compare it to the saturation temperature for your given pressure, and see if it’s higher or lower. That tells you if you’re superheated or subcooled.

Make sense?

[Sam Brown]

When checking some harness connections or even on the board / invertor board. I can’t find a place to test the dc voltage or hertz. Some harness connections, have the wire going into the connector where the wire is not exposed or I’m not able to get a probe in there .

You do sometimes have wires completely encased in a plastic connector, but you can still test those. You just need to have thin micro-leads for your meter. Something like these.

Using very thin leads like that, you can do what’s called “backprobing”, where you push your meter probes into the back of the connector and make contact with the wires that way.

[Sam Brown]

I have difficulty in finding the jumper wire from H1 to the hot light in the ‘wiring diagram’.

The reason you’re having difficulty is because wiring diagrams are terrible for tracing and understanding circuits. This is because of a key difference between schematics and wiring diagrams.

Schematics are an abstract representation of the circuit which show it “as electrons see it”. In other words, it represents each circuit as straightforwardly as possible, disregarding physical realities like molex connectors.

Wiring diagrams are representations of how the circuits exist physically, showing how all the wires tag off of different loads and go through various connectors. This makes it very hard to trace a circuit through a wiring diagram, because that’s not their purpose.

As techs, we almost always use the schematic. That’s the document that’s actually useful for us when it comes to understanding circuits, troubleshooting, and identifying test points. The only situation when you’d want to use a wiring diagram is if you’re tracking down a broken wire or failed harness connector, which is much rarer.

So basically, you should just stick to the schematic. The wiring diagram will only confuse you if you try to use it to understand a circuit.

[Sam Brown]

It all comes down to how many amps are in the circuit you’re jumping. Different gauges of wire have different ampacity ratings — that is, they have a spec for how much current they can carry before overheating. This page explains ampacity and has a nice chart to demonstrate.

For the amount of current in the AC circuits we work with, 12 gauge wire is a safe bet. The only situation where you might want to have a different wire gauge on hand is if you’re jumping something in a low-voltage DC circuit. Much lower amps in these, and often the connectors are itty-bitty, making it hard to get a 12 gauge jumper in there. For these, 18 gauge works well.

[Sam Brown]

Hello Susan,

Thank you for the reply, I was just looking at that schematic and since this is the first time I’ve seen anything like this, I am a little confused on the lines I see where the schematic lists Active and Fixed like your example 16/13/15 but am I to understand the Active number box has a line which goes across the entire page that line is referring to 16 on Cam 8 then does Fixed 13 begin at 6 min. under the Pump box and end at 4 min?

If so then thank you for clarifying if not…

Sounds like you’ve basically got it, but I’ll clarify a bit more. We’ll take the row you gave as an example — the one for “pump” and “low motor”. Don’t worry about those “fixed” and “active” labels. All you need to focus on is the numbers of the contacts, because that’s what’s telling you which switches are closed when during the cycle.

For example, moving to the right along the timer chart, you’ll see that the boxes in the “pump” row are filled in during the pump part of the cycle (naturally). That means that, during that part of the cycle, the timer closes the switch that connects T16 to T13. You can double check that on the schematic. If you look, you’ll see at the section marked 8, the cam number, there’s a switch that can be closed in one of two ways. If it closes one way, T16 and T13 become electrically equivalent. If it closes the other way, T16 and T15 become electrically equivalent. That second one is for running the motor on low speed, as the timer chart says.

Does that make sense?

[Sam Brown]

If the dielectric barrier in the capacitor breaks down and the capacitor shorts, then it would cause issues. The motor would run, at least for a bit, but there would now be voltage drop across the start winding even after the PTC has gone open. This causes excessive current draw and will probably blow the motor’s overload protector.

[Sam Brown]

I don’t believe we have a video showing that exact procedure, but it’s really not any more complicated than what you just stated. You situate the head of the thermistor in a glass of ice water, and then you go to the harness connector on the control board and put your meter probes on the two pins for the thermistor. The way you identify the pins is by using the schematic. That will show you which pin numbers correspond to that thermistor.

[Sam Brown]

Hello MST, in the 3rd video what cause the 30amp fuse to open? I’m assuming it was a loose connection in one of the terminals.

Remember what a loose connection causes: higher resistance. And the more resistance you have, the less current will move through the circuit. So a loose connection would not cause the excessive amps to open a fuse.

Far more often than not, these safety fuses trip for no reason (simply due to age), and that’s what happened in that video. Once you replace the fuse, everything almost always works just fine.

[Sam Brown]

It is a general purpose and pretty reliable test. Hall sensors all work the same way, and they don’t usually go out of calibration — in fact, a lot of Hall sensor problems are due to a break in the wire harness rather than an issue with the sensor itself.

The test would be done while the washer is not running. The machine could be plugged in or not — that part doesn’t matter, so long as the motor is not being powered. Which should be obvious, since you’re spinning it by hand as part of this test.

And of course, you should go to the documentation for the model you’re working on first. They may provide a more specific test routine for their implementation of the Hall sensor.

There’s a blog post at Appliantology with more information about Hall sensors if you would like to learn more: click here to check it out.

[Sam Brown]

Just wondering how is the Convection Fan Motor (letter ‘A”) relay turned on if this fan motor is not running?

The circle marked “A” isn’t the convection fan relay — it’s the convection fan motor itself. That’s our load of interest. The relay is the switch that supplies voltage to the convection fan. What we want to find out with our voltage test is if that relay is closing and supply the convection motor with voltage.

The measurement points that you gave would only tell you if the entire appliance has a valid line and neutral. Where could you do a test that would be more specifically focused on the convection fan motor’s power supply?

[Sam Brown]

When you make a voltage test, you need to ensure that the circuit you are testing is supplied with power. Otherwise, it’s not a live test.

So yes, in your drain pump example, you would want to active a drain cycle or activate the drain pump in test mode.

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