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DonSeattle  
#1 Posted : Saturday, March 15, 2014 9:39:08 PM(UTC)
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DonSeattle

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The compressor tries to start, but doesn’t. There was a blown fuse initially, but the replacement fuse did not blow. I did in between fix a power cord that might have had a short.


Any chance that this compressor is still serviceable? The resistance readings between the 3 pins are 1.1 Ohms (between the compressor pins that are ultimately connected to the line voltage), 18.8 Ohms, and 17.9 Ohms. I expected lower readings base d on Internet info. PTC Danfoss 103N0003 – 115V (originally white ceramic, top half looking rather brown now) plugs onto the compressor and applies 6.9 Ohms (cold) across the compressor pins that measure 17.9 Ohms.


The refrigerator is about 1980 Amana model ESRFC16E mfgr number P7464514W. The compressor (Danfoss FR8.5A?) is labeled as having an internal winding protector. As far as I can tell there is no start capacitor and no run capacitor.


If it helps answer the question, I can borrow a clamp-on ammeter in a couple of days and take a reading.
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richappy  
#2 Posted : Sunday, March 16, 2014 2:03:40 AM(UTC)
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richappy

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Your compressor ohms readings are too high. The top compressor pin is common, bottom left start, bottom right, run. Measure ohms between the top and either bottom pin, should be around 6 ohms. Also, check any pin to ground to see if you have a short to ground.
Measure across the ptc device output pins, should be 5- 7 ohms.
If ok, you can try a Supco hard start kit on this, might start the compressor.
denman  
#3 Posted : Sunday, March 16, 2014 2:51:59 AM(UTC)
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denman

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As richappy said it sounds like your compressor is toast.

I did find a tech sheet for a FR8.5G compressor, it gives the winding resistances as 8.9 and 12 ohms. This would be 20.9 ohms for the in series measurement.

On your unit (if I interpret the readings correctly) has winding resistances of 17.9 and 1.1 ohms with a series resistance of 18.8
THIS FORUM IS DEAD!!!!!!!
DonSeattle  
#4 Posted : Sunday, March 16, 2014 11:12:29 AM(UTC)
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DonSeattle

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Thanks very much for the responses. Are these the type of readings that would fall in what I suspect is the wide range of readings one finds with shorted windings?

Looks like the PTC reading is in the ballpark, but the compressor readings are off, at least compared to the FR8.5G, which I found listed as a 240V compressor (but I couldn't on my own find anything on the FR8.5 G winding resistances). I couldn't find anything on FR8.5A.

There are no shorts from the compressor pins to ground.

On my compressor there are two pins on top and one pin on the bottom, with line connections to top left and bottom, and PTC connecting top left and top right. I think bottom is common, top left is run, top right is start. If I'm right this would give CR 1.1 Ohms, RS 17.9 Ohms, and SC 18.8 Ohms. Using the standard calculations (R 1.1 Ohms, S 18.8 Ohms, and R + S 17.9 Ohms), those readings are inconsistent with good windings. If I assume a short between the run and start windings producing a parallel resistance F to common, then the equations R+F+1.1, S+F=18.8, and R+S=17.9 would give F 1.0 Ohms, R 0.1 Ohms, and S 17.8 Ohms, where R and S are the un-shorted portions of the windings connected to the terminal pins.

In my ignorance, I suppose there is some way failed internal thermal protection could play into this, but I suspect winding damage is the most probable explanation of the observed resistance windings. Bottom line, keeps looking like the compressor is toast.

Thanks again.
richappy  
#5 Posted : Tuesday, March 18, 2014 12:26:45 PM(UTC)
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richappy

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Resistance readings with a 9 volt ohmmeter will not detect burnt windings, voltage too low.
Try a hard start kit on it, but with burnt windings it might not last too long.
DonSeattle  
#6 Posted : Tuesday, March 18, 2014 6:10:13 PM(UTC)
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DonSeattle

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I just have the regular old 9V ohmmeter. Sounds like my best bet is to replace the refrigerator. Thanks again everyone for all the help.
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