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Post by rodamala on Nov 15, 2020 18:42:14 GMT
Acquired non-operating until sold as "It worked 30 years ago when she moved it to the garage". You all know how that goes.
Since bringing it home:
1) Plugged it in unit pulls 1300W then trips out on overload. No action at all with Compressor, only relay (original, still sealed) hum.
2) Initially believed Oil Conditioner was OK as Kill-a-Watt showed an 8 to 12 watt load with control in "OFF" position.
3) Attempted NCG bleed a few times (bear in mind that compressor does not run). Did not heat up evaporator section with trays of warm water. Only gently bled a little gas and when I smelled a whiff of a solvent type smell stopped.
4) Upon further investigation, Oil Conditioner element rang out as open. Ordered replacement from PTS.
5) Removed all 86 year old crunchy cabling and replaced with new SJO type cords. With all wires removed from compressor, winding resistance values (measured using an analog ohmmeter) were 3.2 Ohms and approximately 21 kOhms. I assume motor is not toasted.
6) Fabricated and installed new wiring harness and new Oil Conditioner cable. Took my time and did this right with the exception of grommet installation for the 2 conductor cable going to the 2 knob control relay (grommet was too crusty and could not get it to snap back into place with no working space).
7) Allowed 24 hours for 13W (measured with Kill-a-Watt) heater to "condition" oil in sump. Did not invert unit and apply IR lightbulb to dome. Did not use hairdryer or heat gun. Just gave it 24 hours... still pulling 13W.
8) Moved controller to "ON", same results as when unit was initially checked out. Pulls 1300W and trips out (stalled compressor). There is no sound at all of compressor even attempting to start. Starting relay seems to be in good order, although original magnet wire of armature shows very slight discoloration. I do not believe it is fried, it does operate the contact, but I see no telltale arc. The contacts appear to be in decent condition, not pitted or eroded, but they are black.
9) Gently sanded contacts on starting relay with 400 grit sandpaper and attempted startup again. No dice.
So that is where I am at, and wish to pose a few questions regarding NCG bleeding on a stalled compressor unit.
1) Do I perform NCG purge with the heater element in operation? As info, the unit is outside and ambient air temperature today is 48°F.
2) Insinuation in manual and in posts here is that the refrigerant should be at a slight vacuum... does this mean when the compressor is running the float chamber header where the NCG accumulates should also be less than atmospheric pressure (makes no sense to me with all NCG bleed guidance I have seen here and in videos, but my compressor is not running).
I do not want to overbleed the system and exhaust all the MF to atmosphere.
I have not gotten to the point of disconnection of the heater and applying 220VAC, nor do I have a "3 in 1" capacitor, an "Annie" unit or a medium HP motor to phase shift my compressor.
I am trying to do this in a methodical fashion... and where I am at now is "probably" a proper NCG procedure for a unit that has a compressor that is stalled or otherwise locked.
Sorry this is so long. I just wanted to spew all the information I have on this so far so someone who has been exactly where I am at can respond and give guidance on my next step of this process.
Rod
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Post by ChrisJ on Nov 16, 2020 13:31:30 GMT
You don't hear any hum or buzz from the compressor at all?
The motor stays totally silent?
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Post by rodamala on Nov 16, 2020 22:34:50 GMT
The hum of the starting relay is all I hear.
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Post by ckfan on Nov 16, 2020 22:54:04 GMT
The winding resistances sound a little off. The start winding should always have a higher resistance than the run winding. Is that what you got? From what you wrote it seems like they are equal. If you had a way to measure current, like with an amp clamp, you could determine if both the run and start windings are passing current right. I know that with my CA, it was locked up and I had to shake it violently in order to break it free while I had power applied. That fixed it and it still works fine. I’m not saying this is the preferred method. It isn’t. But it worked for me. Right now we just have to determine if your problem is mechanical (binding or NCGs) or electrical.
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Post by coldspaces on Nov 17, 2020 1:04:28 GMT
You must have it out of a vacuum to do a bleed. Unit must be warmed to get positive pressure or air will go in instead on NCG coming out. The condenser needs to be over 90F to be out of a vacuum. You listed one winding as testing 21,000 ohms. That is way to high.
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Post by turbokinetic on Nov 17, 2020 6:05:29 GMT
You must have it out of a vacuum to do a bleed. Unit must be warmed to get positive pressure or air will go in instead on NCG coming out. The condenser needs to be over 90F to be out of a vacuum. You listed one winding as testing 21,000 ohms. That is way to high. If you have 21KΩ on any of the three motor terminals, you've got a problem. I would highly recommend to revisit the wiring and be sure that you're testing the motor its self and not including other components in the test. The 3-core cable from the relay area goes to the motor, but the common wire has the thermostat / overload protector in the circuit. If the contacts are not in good condition, they can give very erroneous readings with a meter; even though they will pass current when a higher voltage (120V) is applied to them. Measured at the terminals on the bottom of the compressor dome, the resistances should be around 3 or 4Ω; run-to-common; and higher (10Ω or so) for the common to start terminal. None should be much more than 10Ω. If you measure any sort of KΩ reading at the motor terminals, that is considered an open winding. If the condenser was not warm; and you were still able to get pressure to escape, the unit has a significant NCG buildup. I would try to get it to start and run, then follow the bleeding procedure. There will always be some methyl formate odor if you smell up close enough, especially at first when the NCG is severe. Sincerely, David |
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Post by rodamala on Nov 20, 2020 13:58:49 GMT
All, I will recheck the winding values. I had not written them down. I tested with all wiring disconnected, right at the compressor lugs.
Now that I think about it, I believe that it was NOT 21 kOhms... but 21 Ohms, because I seem to recall one coil was 3.2 Ohms, the other was 21 Ohms, and across both coils was in the correct neighborhood of expectation for 2 resistances in series.
I miss my Fluke meter. All I had was a junk throwaway Chinese meter from Wal*Mart.
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Post by rodamala on Nov 20, 2020 19:22:24 GMT
Because bottom of compressor is no longer accessible, I discoed the red and white leads at the starting relay. I turned the control knob to ON to get continuity on the common.
Red to Black resistance is 3.5 Ohms.
White to Black resistance is 25 Ohms.
I still have pressure in the system and am venting the gas (1 minute vent through mineral oil, 3 minutes closed). I do smell Methyl Formate, and the gas escaping is flamable.
I have all power off to the unit right now. I imagine the oil in the sump still has residual warmth from the oil conditioner which has been pulling 13 Watts for over 48 hours.
Do I keep venting this way until there is no more pressure? Do I do this after the oil in the sump is at ambient air temperature or is it OK to do while oil conditioner is powered and sump is (assumedly) warm?
Rod
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Post by ckfan on Nov 21, 2020 2:24:05 GMT
I think you’re fine to let the heater go while you purge. It should definitely be well into a vacuum when it isn’t running. I would think you would be fine to purge just until the point where it starts bubbling really slowly. That way you don’t suck any air in for sure. I’m not sure that 25 ohm reading sounds good. I would expect it to be much lower. That almost sounds like the reading you would get across both the start and run windings.
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Post by turbokinetic on Nov 21, 2020 3:09:53 GMT
Because bottom of compressor is no longer accessible, I discoed the red and white leads at the starting relay. I turned the control knob to ON to get continuity on the common. Red to Black resistance is 3.5 Ohms. White to Black resistance is 25 Ohms. I still have pressure in the system and am venting the gas (1 minute vent through mineral oil, 3 minutes closed). I do smell Methyl Formate, and the gas escaping is flamable. I have all power off to the unit right now. I imagine the oil in the sump still has residual warmth from the oil conditioner which has been pulling 13 Watts for over 48 hours. Do I keep venting this way until there is no more pressure? Do I do this after the oil in the sump is at ambient air temperature or is it OK to do while oil conditioner is powered and sump is (assumedly) warm? Rod Those resistances sound good, actually! If the unit is cool, and the heater is off, (below 80°F) there should be vacuum in the unit. Keep releasing pressure until there is no more pressure, ensuring the system does not draw air in. Once the pressure is equalized, you need to close the bleeder, run the unit and heat it up to do the factory purge procedure. The NCG which builds up is flammable because it is mainly hydrogen gas. Sincerely, David |
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Post by rodamala on Nov 21, 2020 14:18:35 GMT
Well, shortly after my post I went back to the unit to continue bleeding what may or may not be a large amount of built up NCGs.
This was after removing power to the unit so I could reread compressor motor winding resistances and report here.
The heater had been off for "a while" (30-60 minutes), and I left it off and attempted another NCG purge. This time, there was no bubbling of escaping gas as before when the heater was on.
Please note in all of this work that the compressor is not running.
I have to assume at this point I am at a point where I may briefly apply 220VAC to attempt to awaken the compressor motor... but first, I have the heater back on power to see if more gas may be vented.
I just do not want to be venting off MF gas, which is what I believe I had been doing as the gas coming out produced a blue flame when an open flame was brought near it.
All the guidance on compressor rattles or frost line on the evaporator coil can't be used until I kick the compressor motor on.
Complication for me is a windstorm took down the two 90+ year old white pines in front of the house, and the driveway is blocked as I deal with that crisis... meanwhile it is 40°F ambient and I have another 2 cords of maple to split for heat in the house.
I just want to be methodical with the fridge rehab. Did I mention that I do not want to vent out all my precious MF? I really do not want to have to recharge it. I don't have the time resource to deal with that on top of everything else.
Rod
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Post by rodamala on Nov 21, 2020 15:04:29 GMT
Unit was in vacuum just now with only heat being the oil conditioner.
I took 400 grit wet-dry sandpaper to the starting relay contacts, and when tried to start, I did hear "something" from the compressor, like a partial turn of the motor... nothing continuous. I tried again and nothing from the compressor, but did note an arc across the contacts when closing (this is new).
I think I am getting close to something here. I hope too much air did not suck in on my last bleed attempt. I just want the compressor to start and run, warm everything up and go from there.
Service manual is not detailed about how to apply 220VAC "momentarily". I assume to protect the new oil conditioner that I disconnect it... but everything else is going to be "momentarily" OK.
Rod
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Post by turbokinetic on Nov 21, 2020 15:12:22 GMT
Unit was in vacuum just now with only heat being the oil conditioner. I took 400 grit wet-dry sandpaper to the starting relay contacts, and when tried to start, I did hear "something" from the compressor, like a partial turn of the motor... nothing continuous. I tried again and nothing from the compressor, but did note an arc across the contacts when closing (this is new). I think I am getting close to something here. I hope too much air did not suck in on my last bleed attempt. I just want the compressor to start and run, warm everything up and go from there. Service manual is not detailed about how to apply 220VAC "momentarily". I assume to protect the new oil conditioner that I disconnect it... but everything else is going to be "momentarily" OK. Rod It does sound like you're moving in the right direction! I would disconnect the oil heater for the 240V boost. As far as momentary; the best way is to give it a series of pulses (about half a second each). No more than 3 or 4 at a time before giving it a cooldown of about 5 minutes. If it starts up, go back to standard 120V power and see if it will run again. |
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Post by elec573 on Nov 23, 2020 3:14:48 GMT
monitortop.freeforums.net/thread/943/d2-a16This is a dr not a ca , I went through the process to determine it’s not working. I would recommend rechecking the windings and also to ground . Remove the controls and take your reading from there . You want to make sure the motor has not shorted out before you sink money into it !
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Post by rodamala on Nov 23, 2020 14:39:35 GMT
monitortop.freeforums.net/thread/943/d2-a16This is a dr not a ca , I went through the process to determine it’s not working. I would recommend rechecking the windings and also to ground . Remove the controls and take your reading from there . You want to make sure the motor has not shorted out before you sink money into it ! Discoed leads at starting relay and checked continuity to ground, using the bronze top of the float chamber (Bristol key plug location) as my "ground". I first rang from that location to the head of one of the long machine screws that bolt the starting relay to the side of the condensing coil, and that showed continuity, so I assume I have a proper ground reference (chassis ground), although there is no actual grounding to earth of the chassis. Tested all three leads on the 100kOhm scale and there was no wiggle at all of the needle on the Chinesium Wal*Mart analog meter. I may have forgotten to snap the control to ON, however, so may not have actually checked the common to ground. Regardless, I moved forward, reattached the leads at the starting relay, leaving the heater unhooked, then rigged up 220VAC to an extension cord. Plugged it in and instantly the compressor came to life! Immediately unplugged it and put it on 120VAC and it starts and runs! Baby steps here. Here is a link to a 17 second film I made. It is not exciting, but you can hear the compressor, and hear the "waterfall" sound in the evaporator: youtu.be/eKmOBFV9rhgThe dome was verified as becoming warm. The unit is presently on my front porch propped up on bricks and boards (off the cabinet) and the ambient air temperature is 32° F this morning. I played with the thermostatic control, but no position on the dial snapped the compressor off as I would expect, especially when the sensing tube is already at 32° F. I need to investigate operation of that relay... when I turn the ON-OFF knob to the "Defrost" position, it does not spring back to ON the way (I seem to recall) that it did before the compressor was running. It now seems to click into place on "Defrost", but it does not turn the compressor off. Like I said, I need to read up on the operation of that control. Anyway, having the compressor running, I left it running and went to get a cup of celebratory coffee. When I returned the compressor was off. Turning the control knob to OFF then ON again restarted it. Baby steps here, guys... but the good news is the compressor motor came to life, which is a huge step as far as I am concerned. Rod |
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