Variable Speed Compressor Issue!

[EchoEleven]

I have a question I wonder if a master tech out there could answer. I have an Electrolux EW23BC85KS4. Everything is running except the compressor. I am getting 120vac to the inverter, and 13vac to the inverter on the control side, but the compressor will not run. I have checked the windings and they all read 15ohms. My question is, I always thought the inverter received DC voltage at the control part, and 120vac from the line, but I am getting 13vAC at the control connector. I am leaning towards it being a bad inverter, just wanted to make sure before I purchase one. The condenser fan is NOT running, and not sure if it supposed to be on a variable speed system if the compressor is not running.The previous tech replaced the main control, but I believe it was the inverter all along. The only thing I am confused about, when I was reading about variable speed compressors it said I should be getting 10-15vac AND 4-6vdc on the control wires. I did not think this was possible to carry DC AND AC on the same line? Am I doing something wrong? Any help would be greatly appreciated!!

[Hiroshi]

The wiring diagram for this model shows 120VAC L1 in and 12VDC as the signal voltage to the inverter, so AC voltage on your signal line is incorrect.  The inverter and fan receive the 12VDC, they don't produce it, so the finger is pointing at the main control board...

FrigidaireEW23BC85KS4--pub242173200.pdf

[EchoEleven]

That's exactly what I thought...until I replaced the board and the problem is the same, voltages are the same..no chance on 2 boards, 1 of them brand new, having the exact same issue...on the samarui tech forums it says the inverter is supposed to get 10-15vac AND 4-6vdc..it's the most popular link when looking up how to test an inverter.

[EchoEleven]

And I assumed this is incorrect since to my knowledge you cannot have 2 voltages on the same line..but everywhere I look they all say it's supposed to get 10-15VAC and 4-6VDC?? I hardly get stumped, but this ones got me. If I supply dc voltage manually to it via an external source, should it start the compressor? Or does it have to be at a certain frequency?

[Hiroshi]

 What is the voltage reading at the condenser fan motor? Is the machine definitely set to cool?

The 120VAC is what the inverter uses to power the compressor to "run." The DC is a signal used to control/monitor run speed. Supplying external DC voltage would not make the compressor run as far as I know... 

I have had incorrect boards given to me by the supplier, be sure you have the main control intended for inverter compressors by comparing the new one with your old to be sure you have an exact match

 

 

[EchoEleven]

I believe I figured out whats going on. The previous tech that was out on this refrigerator put a side by side power board in a french door model..totally different part numbers. I am going tomorrow to replace the board with the correct one..Hopefully it did not screw anything up!

[Hiroshi]

Nice job, I think you are on track... It shouldn't damage anything to have a slightly incorrect board in the unit for a bit

[EchoEleven]

Do you think it harmed the inverter by supplying 13VAC to it instead of dc?

[Hiroshi]

You can only tell by installing the new board and observing compressor function, the inverter may be bad too, but I am guessing you will be ok. If the inverter doesn't fire up within 7 minutes of being energized, take your voltage measurements to verify the main board is doing it's part and be sure the unit is not in a defrost cycle. I will generally give any main control 30 minutes to start a cooling cycle (20 min for defrost/ 7 minutes dwell time) just to be sure it wasn't in another mode when I installed it.  The cheapest GE inverter is interchangeable with yours so don't pay 400 bucks for a new inverter....Part number: WR49X10283  if it turns out yours is ruinated.

[BrewHobbyTech]

Welcome to the Twilight Zone.........am I allowed to swear here?? OMFG!!!!!!!! Yeah,  inverter boards and some/most/all of these newer designed refrigerators are freaking insane.....and not only are they screwing the customers.......they are screwing the technicians just as bad. I'm not gonna get into details, but I would/could make a pretty good guess that, yes, it sounds like your converter board is bad. One question for ya though, and for others.......the unit is unplugged.....and removed from the wall....and bottom panel removed(doesn't have to be)......but then plug it in and notice if condenser fan motor comes on for a second.......or even blinks(fan blade starts or just barely moves)......92+% chance you have a bad inverter board. I don't know if this will help anyone out, but it should be good for a rule of thumb......and in the future I may go into more detail........

[EchoEleven]

It turned out to be just the main control. Some previous company who "Tried" to fix it installed a control board for a side by side with a non variable speed compressor...This is a french door with a variable speed..Plus when I removed the old board, somehow when he was installing it he messed up the harness and knocked loose a capacitor on the board. Once I installed the new board and waited about 20 seconds, it fired right up. This goes to show you, sometimes it's just so simple, especially if someone else has already worked on it! ALWAYS check to see what another company has done first, before you go digging and wasting hours of time. Thanks again for all of your help!!

[EchoEleven]

I also just wanted to add something, and this isn't the correct thread for it, but I just have to. Maybe it's done all the time, maybe I just had a stroke of genius, I dunno. But I was on a call the other day on a maytag refrigerator that was overcooling in the fresh food. The temps "said" 46 degrees but it was actually 32, so I suspected the thermistor in the fresh food. Tested the thermistor, it was fine. So obviously it was the control board. Needless to say I got online and seen that the board was NLA. So, I pondered for a minute, thats when I thought, if the temps are roughly 14 degrees off, what if I add a 4.7kohm resistor inline with the thermistor? BAM, soldered one in right at the thermistor and temperature readout was perfect! Just adding this for you techs, maybe you already realized this, maybe it will never matter because this type of scenario is rare. Just thought I would add it! Thanks again!

[Hiroshi]

Great tip, considering the display read-outs are kind of arbitrary, in that they do not always reflect reality, this could come in mighty handy to satisfy a picky customer who wants everything to LOOK ok, besides just operating correctly. It is the electronic version of the old thermostat knob adjustment... I like it.