Compressor pulls higher amps on test cord?

[Shira]

Hi! I'm playing with a dehumidifier and  Found that the compressor pulled 2 amps more while on the test cord then when running through its normal circuit. Pretty consistently. I think I monitored it for a minute or two.  I don't see a run capacitor or anything like that in the circuit.  It wasn't long enough that I would think the fan not being on would be an issue. Any ideas why that might be the case?

 

 It's also not working and the compressor seems to heat up pretty fast.  I monitored it for 20 minutes or a half an hour or so and it was up to 200° and still seemed to be climbing. 

[Shira]

It kinda seems like the start winding is not being dropped out, but wouldn't it be pulling LRA then? Also the capacitor tested good by the microfared reading things on my meter, at least, as best as I could figure to test it from YouTube. 

[Shira]

[Shira]

What does this symbol mean inside the compressor? 

[Terry Carmen]

That's an internal overload protector. Not sure why it would draw more current on a test cord.

[Quick]

8 hours ago, Shira said:

Hi! I'm playing with a dehumidifier

Yes you are. I can see you like messing with that stuff don't you.  I like that Fluke. You need to hook up with this bunch man. I can tell this stuff interests you. There will always be a need for  good techs. I can't tell exactly what measurments you're trying to take. I don't understand for sure what you got gone on with all that but I lean toward a bad compressor. Just a guess there. This outfit here (MST Master Samurai Tech can give you all the know how you could ever need as to when, where, and why to take electrical measurements properly.

Good luck with all that. 

Be careful them electrons can be mean. 

 

 

Edited July 30, 2023 by Quick
grammer and spelling

[Budget Appliance Repair]

@Shira I think it might be the way you have the test cord and switch connected into the compressor circuit.

I can't tell from your pictures were you have the other side of the switch connected to and where you have the test cord other wire going to.

The diagram is kind of strange also - I don't see a start device in the circuit.  The capacitor at the compressor is a run capacitor and when put into the system correctly it would lower the running amps, (possibly the way you have your test wiring hooked up you are eliminating the run capacitor from the circuit causing it to run at the 2 amps more then when running thru the devices correct wiring).

Even if you were running both start and run windings not dropping out the start windings you won't get the 29 LRA (Locked Rotor Amps), because the rotor isn't locked but I would expect to see much higher then 5.3 amps if both windings were staying powered.

@Samurai Appliance Repair Man Can the run capacitor work as a start device on startup, fully energizing the start and run at startup then once the unit is running the run capacitor just cause the phase shift to run more efficiently.   I see no other way without a start device in the circuit for this to happen.

[Shira]

3 hours ago, Budget Appliance Repair said:

@Shira I think it might be the way you have the test cord and switch connected into the compressor circuit.

I can't tell from your pictures were you have the other side of the switch connected to and where you have the test cord other wire going to.

The diagram is kind of strange also - I don't see a start device in the circuit.  The capacitor at the compressor is a run capacitor and when put into the system correctly it would lower the running amps, (possibly the way you have your test wiring hooked up you are eliminating the run capacitor from the circuit causing it to run at the 2 amps more then when running thru the devices correct wiring).

Even if you were running both start and run windings not dropping out the start windings you won't get the 29 LRA (Locked Rotor Amps), because the rotor isn't locked but I would expect to see much higher then 5.3 amps if both windings were staying powered.

@Samurai Appliance Repair Man Can the run capacitor work as a start device on startup, fully energizing the start and run at startup then once the unit is running the run capacitor just cause the phase shift to run more efficiently.   I see no other way without a start device in the circuit for this to happen.

Thanks so much!!! I did not realize that was a run capacitor! 

I tried both the ground of my outlet (sticking the lead in the round hole of the receptacle) and the ground of the appliance (which I realize should be the same thing) and got the same 5 amp reading. I don't think I tried Nuetral. If that is a run capacitor, I think that would make sense in the amp difference! But does indeed bring up a new problem in not having a start capacitor. 

I had the switch on the start winding, according to the wire colors of the diagram (yellow) and the black cap that went over the compressor (it has R S and C bubbles on it where each one goes). I don't think I paid attention to common vs run in hooking up the other two leads. Could that make a problem?  

How can I find out if either 3 or 5 amps would be a normal running amperage for this compressor? I'm curious if the regular running amps (currently 3) are within spec, since the unit does not collect water in it and the compressor seems to overheat relatively quickly (on that note- why is there no compressor fan?) but everything else seems to work and be cycling normally (as best as I can figure with information given/found online - compressor on for about 10 min, off for ~4ish min, fan is running, display looks normal...). 

Any chance N1 has anything to do with controlling the start-up? I don't see how it would since they show it in the same circuit as both the run and start though... very confusing. Thanks for letting me know I'm not crazy.  

[Shira]

13 hours ago, Quick said:

Yes you are. I can see you like messing with that stuff don't you.  I like that Fluke. You need to hook up with this bunch man. I can tell this stuff interests you. There will always be a need for  good techs. I can't tell exactly what measurments you're trying to take. I don't understand for sure what you got gone on with all that but I lean toward a bad compressor. Just a guess there. This outfit here (MST Master Samurai Tech can give you all the know how you could ever need as to when, where, and why to take electrical measurements properly.

Good luck with all that. 

Be careful them electrons can be mean. 

 

 

Thank you! I actually did a year in the field and took MST training. But I'm a bit out of practice because I then decided I really don't like the work. x) Too much pressure, too much giving bad news to people I like, too much evil corporations. I'm a lowly maintenance tech now at a non-profit that gives lots of vacation time.  I was leaning toward sealed system issue since everything else seems to be cycling correctly, but I wish I had just a little more information then I do! 

[Shira]

Not to spam this forum, but is this green stuff and weird crystally looking pieces normal? I think the green stuff might be just oxidation.  Not sure what the other stuff is.  

[Budget Appliance Repair]

Almost looks like bubbles, (leak), in some of those grey color paint, (or sealing stuff?), maybe this thing has a leaky evaporator that someone patched up?

Compressors doesn't need a start capacitor, (some use them or for hard starts you can add one - like a 3-N-1 start pak to get more life if you have a tight worn out compressor that isn't starting with the factory setup).

[Samurai Appliance Repair Man]

Am I seeing two capacitors by the compressor in the photos in the OP: a run cap and a start cap? What's printed on each of these components? 

The large silver cap looks like a start cap. The farads will tell the story. In the appliance world, start caps are in the range of 200 uf whereas run caps are in the range of 10 to 20 uf. 

[Budget Appliance Repair]

@Samurai Appliance Repair Man I'm pretty sure the large silver can capacitor is for the blower motor.

Can the capacitor on the compressor work as a start device/start capacitor at full current inrush than as a run after the compressor is running, (that's what I was asking/noted in my original post - the diagram doesn't show a start device, just the capacitor on the compressor start/run terminals).

EDITED TO ADD: looking closer at the pictures, it looks like maybe the large silver can capacitor is for the compressor, (Yellow and ? color wires) and the small square is the fan run capacitor, (the Brown or Red wire that can be seen).

Edited August 2, 2023 by Budget Appliance Repair

[Shira]

About to go to bed but here are some more pictures I took before.  Didn't get one of the little capacitor. 

[Budget Appliance Repair]

Yellow wire for sure and the color is hard to tell on the other but it does appear it could be blue and I'm pretty sure I see two blue wires going into that spade connector.

@Samurai Appliance Repair Man I've never seen a compressor setup without a start device - is this a bigger sized compressor, (maybe what is called a Scroll compressor), that is using this larger capacitor as a start device and run capacitor?

[Terry Carmen]

FWIW, the diagram doesn't show any sort of start device. Just the two windings and one capacitor

[Samurai Appliance Repair Man]

It's definitely a split phase motor with a main and start winding. That much is shown on the wiring diagram. That being the case, the motor still requires a start device to take the start winding out of the circuit. Would be good to see a closeup pic of the smaller square device that looks like a run cap. Would like to read what's printed on it. 

I'm wondering about the accuracy of the wiring diagram. 

[Budget Appliance Repair]

10 minutes ago, Samurai Appliance Repair Man said:

Would be good to see a closeup pic of the smaller square device that looks like a run cap. Would like to read what's printed on it. 

Pretty sure the smaller one, (from the wire colors), is definitely the fan motor capacitor.

[Budget Appliance Repair]

19 minutes ago, Samurai Appliance Repair Man said:

That being the case, the motor still requires a start device to take the start winding out of the circuit

That's why my question about can the 50uF capacitor work as a start device on inrush current powering the start windings then after the split second it takes to start and the capacitor is fully charged then work as a run capacitor making the compressor run more efficiently.  Also the way the overload protector is shown on the diagram is unconventional also, not in the wiring like normal but internal to the compressor itself, same as the fan motor overload protector.

EDITED TO ADD: Googling the compressor number it is a Rotary Compressor.

Edited August 4, 2023 by Budget Appliance Repair

[Samurai Appliance Repair Man]

5 minutes ago, Budget Appliance Repair said:

That's why my question about can the 50uF capacitor work as a start device on inrush current powering the start windings then after the split second it takes to start and the capacitor is fully charged then work as a run capacitor making the compressor run more efficiently. 

I know what it is-- I don't know why I didn't think of it before. This is a special type of motor called a Permanent Split Capacitor (PSC) motor. Same type of motor used on fans, some dishwasher wash motors, and the Whirlpool VM washer. The giveaway is 1) no start device and 2) oddly sized capacitor-- it's larger (in farad rating) than most run caps and smaller than most start caps. They use these motors when there's a wide range of torque requirements. The caps used with PSC motors function essentially as you described. 

[Quick]

3 hours ago, Samurai Appliance Repair Man said:

I don't know why I didn't think of it before. This is a special type of motor called a Permanent Split Capacitor (PSC) motor.

Seems like a strange choice seeing no need to reverse the motor?

Edited August 4, 2023 by Quick

[Samurai Appliance Repair Man]

2 minutes ago, Quick said:

Seems like a strange choice seeing no need to reverse the motor?

Are you saying that PSC motors are only used in applications that require CW and CCW shaft rotation? How about dishwasher wash motors? How about fans? PSC motors are used in these and many other non-reversing applications. 

PSC motors CAN have motor shaft rotation reversal but it is not an inherent property of these motors. PSC motors are still split phase AC motors like all the others we deal with-- still has a main and start winding. The only difference is in the capacitor sizing-- choosing a capacitor size that lets both windings stay in the circuit. So no start device needed, either. The tradeoff is lower efficiency. 

The Whirlpool VM washer reverse rotation only because extra circuitry was added to make it happen. If you're interested, you can learn more in this workshop recording: https://appliantology.org/topic/60013-webinar-whirlpool-vm-washer-bi-directional-psc-drive-motors-monday-september-19-7pm-et/?do=findComment&comment=352387

 

[Quick]

I will sure check that out. You introduced me to this PSC motor. Poor mans inverter system in the case of the VMW.  So I guess that's why I was thinking that. I appreciate you. Thank you. But heck yes. I see things a little better now. 

[Quick]

5 hours ago, Samurai Appliance Repair Man said:

https://appliantology.org/topic/60013-webinar-whirlpool-vm-washer-bi-directional-psc-drive-motors-monday-september-19-7pm-et/?do=findComment&comment=352387

 

I think I was the one that inspired you to choose that subject matter at the time when I questioned you about the use of the word (pulse). I guess that's why I considered it used as a one trick pony. I'll be watching for it in other applications. Good stuff. 

[Nathaniel Peterson]

10 hours ago, Samurai Appliance Repair Man said:

I know what it is-- I don't know why I didn't think of it before. This is a special type of motor called a Permanent Split Capacitor (PSC) motor. Same type of motor used on fans, some dishwasher wash motors, and the Whirlpool VM washer. The giveaway is 1) no start device and 2) oddly sized capacitor-- it's larger (in farad rating) than most run caps and smaller than most start caps. They use these motors when there's a wide range of torque requirements. The caps used with PSC motors function essentially as you described. 

From doing HVAC for a couple years you're correct it's exactly IMO like a blower motor in a furnace that has a capacitor. The reason this capacitor is bigger is because it's for pumping refrigerant. So what I gather just like a blower motor in a furnace there's two wires just for the capacitor and the speed taps are controlled by the board depending on load the unit is calling for. Am I correct?