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Hi Brian,
Sorry for the delay in getting back to you — you’re basically spot-on. The only correction I have is to this statement:
If it was working correctly you would read 0 v because the voltage is dropped across the evaporator fan.
The reason you read 0 VAC across the contacts at the Jazz board is because the switch is closed. A closed switch should have no voltage difference across it — it acts just like a section of wire.
Let me know if you have any more questions.
Hi Davon,
That lid switch is very confusingly drawn, and it’s a situation where you have to use your knowledge of how circuits have to work in order to puzzle out what’s going on. I’ve explained how it works in more detail in this post: https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/mod-3-unit-1/
Whether or not it would spin at all would depend on the programming of your specific board’s algorithm. But yes, in general, the Hall effect sensor would be something to check when you have a machine that’s failing to get through load sense.
Thanks for your feedback! We hear you loud and clear, and we’ve actually just added some more in-depth material on top-loader drive assemblies, using a Whirlpool VWM as an example. That’s available right now in the unit on top-load drive systems.
There are a few different ways that manufacturers can implement load sensing in both front-loaders and top-loaders. They always do so using surrogate parameters — that means that, rather than actually measuring the weight of the clothes, they instead measure another variable from which the computer board can approximate the weight of the clothes.
The most common way of doing this is by energizing the motor briefly, then letting it come to rest and timing how long it takes to spin down. More clothes will cause the drum to spin down more quickly, which tells the control board approximately what weight of clothes to accommodate.
Make sense?
Good Deal,? Is the filter dryer the same thing as the heat exchanger
Not at all — they are two completely different sections of the sealed system that serve different purposes.
The filter dryer does just what it sounds like. It both filters solids and grit from the refrigerant and removes moisture from the system.
The heat exchanger, on the other hand, is just a section where the capillary tube going to the evaporator is bonded with the suction tube coming from the evaporator. The idea here is to remove heat from the capillary and transfer it to the suction tube to improve the efficiency of the system.
Ok, no big deal. It just confused me a little on the question since there appears to be two right answers depending where I look.
That question is making a distinction between the pressure after the meter regulator (which we gave as 7″ WC) and the pressure after the appliance’s own regulator (which we gave as 3-5″ WC). The video that you’re referencing is talking about a meter regulator, which is why we have that note mentioning that the pressure would be 5-7″ WC.
Since the question is asking specifically about the pressure after the appliance’s regulator, 3-5″ WC would be the only correct answer.
The exact pressures will vary a bit from manufacturer to manufacturer. What we gave in the unit was some general specs. The important takeaway for you is just that natural gas is used at lower pressures than LP.
In the video on evaporator fans in Unit 1.8 the first video mentions that the fan has a DC power supply which confuses me. Can you clarify please?
Small-scale BLDC motors, like the kind you find used as evaporator fans, are built to run on a 12 VDC power supply. These small BLDC fans do still have an inverter board on them — it’s just built into the fan itself. That little built-in inverter board takes its power supply and inverts it into electronically commutated AC to run the motor, just like a larger scale inverter does.
If any part of that still isn’t clear, let me know.
We’ve got a lot of stuff on diodes that should help you understand them. Here’s a recording of a webinar we gave about diodes over at Appliantology:
Also at Appliantology, I’ve put out a blog post explaining diodes in detail. Click here to check it out.
Good catch! I’ve clarified my previous reply.
The point does stand, however. Due to friction, you do lose some pressure between the evaporator and the compressor inlet, so using that pressure to calculate saturation temperature will still be only an approximation.
1) If another component in the stove ends up grounding to the chassis, would that cause the flame detection system to think there is no flame and keep sparking?
Depends what component we’re talking about. Is it a load or conductor with line on it? If so, you would get a short, and that would cause a lot more problems than just with the reignition module.
2) Also, is the spark voltage always ac?
In modern reignition systems, yes. It needs to be AC for flame rectification to work. Older reignition systems used high-voltage DC, however.
Without a good evaporator thermistor, it’s going to be tough. You can approximate with either a gauge at the compressor inlet or an IR gun, but neither would be very accurate.
By the time the refrigerant has reached the compressor, it will have lost some pressure due to friction and gained some superheat. To calculate the saturation temperature accurately, you would want to use the pressure at the inlet to the evaporator, since you know that the refrigerant will be at saturation there and the pressure and temperature will correspond exactly.
I do see how the wording could be confusing, but that question isn’t saying that PR1 and DLB are EEPs — it’s saying that those are the two test points you would put your meter leads on. When we say that they’re EEPs, we’re referring to the fact that each one is an EEP for measuring across that element. In other words, rather than having to disassemble the unit and put your leads directly on either side of the element, you can simply use PR1 and DLB to do your test. PR1 is an EEP for one side of the element, and DLB is an EEP for the other.
Make sense?
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