Anyone have troubleshooting knowledge of refrigerators?

[caphair]

My GE refrigerator model# GDSC0KCXARWW stopped cooling. It's a bottom freezer refrigerator.

Both evap and condenser fans run. I do not hear the compressor. Hear an occasional click sound I think coming from the sold-state relay.

I've ohm tested the 3 prongs on the compressor, one way reads 5 ohms the other 7 ohms and third way a total of them at 12 ohms. No continuity when when testing to chassis of compressor so it's not showing any shorts.

With the relay disconnected and probing at bottom common connector with negative lead of volt meter, I get 40v on the start terminal that slowly tapers down and a consistent 115v on the run terminal.

Is that normal run voltage or should it be higher? Trying to determine if the relay/overload is working properly. It does rattle when shaking but I'm not sure if that test is feasible for a sold state relay or not.

[stj]

Re: Anyone have troubleshooting knowledge of refrigerators?

solid state relays dont click.
foto of it would help.
any motor-cap for the compressor?

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

There's a "run" cap attached to the relay. The clicking is the overload which is basically a bimetallic switch. The relay itself uses a triac.

I'm not home currently but can provide pics later. Do you know if 40v on the start terminal is normal or if both run and start should have 115v on them?

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

There's a "run" cap attached to the relay. The clicking is the overload which is basically a bimetallic switch. The relay itself uses a triac.

I'm not home currently but can provide pics later. Do you know if 40v on the start terminal is normal or if both run and start should have 115v on them?

Also a wiring diagram would help,if they have one attached to the refrigerator.

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

I don't see a wiring diagram. Here's the relay (cap removed) and the circuit board. Not shown is the overload which is a PTC type that uses a metal button that springs up disconnecting the contact.

The overload is tied directly to the Line terminal and the capacitor and circuit board are connected through the Neutral terminal. I'm wondering if the resistance of the overload has gone up causing the drop in voltage on the start line or if the triac is failing causing the voltage drop?

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

I don't see a wiring diagram. Here's the relay (cap removed) and the circuit board. Not shown is the overload which is a PTC type that uses a metal button that springs up disconnecting the contact.

The overload is tied directly to the Line terminal and the capacitor and circuit board are connected through the Neutral terminal. I'm wondering if the resistance of the overload has gone up causing the drop in voltage on the start line or if the triac is failing causing the voltage drop?

So if you go to this site they will show you how to test the compressor winding and how to test the PTC device. To me it sound that the compressor has open windings. I would check that first. If that is good then I would suspect the start .15 uF start cap. The PTC sounds like it is doing what it is suppose to do, heat up and break the start circuit. Because the motor is not starting the PTC continues to try and start the compressor motor.
https://www.youtube.com/watch?v=ZTKpYdFKPFE

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

Compressor windings test good.

My thing is the start terminal of the relay only getting 40v. Shouldn't it be 120v as well as the run circuit?

Does anyone know how this solid state relay works? It looks like line and neutral are only wires connected to it so what's triggering the gate of the triac?

[budm]

Re: Anyone have troubleshooting knowledge of refrigerators?

Compressor windings test good.

My thing is the start terminal of the relay only getting 40v. Shouldn't it be 120v as well as the run circuit?

Does anyone know how this solid state relay works? It looks like line and neutral are only wires connected to it so what's triggering the gate of the triac?

It looks like there are two large ports and two small ports that may have Male pins going to those port for control. Need to see how that module is connected to the mounting plate or what ever.
No wiring diagram on the back of the fridge?

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

Compressor windings test good.

My thing is the start terminal of the relay only getting 40v. Shouldn't it be 120v as well as the run circuit?

Does anyone know how this solid state relay works? It looks like line and neutral are only wires connected to it so what's triggering the gate of the triac?

So my understanding of the start circuit is that the voltage builds with time in order to kick in the run circuit to take over. How much voltage is the compressor getting at this time, the start windings of the compressor? Solid State Relays have function differently depending on how they are set up. Basically they are operated at small voltages and current and many times they have a photo optic switch to isolate the input from the output. With a Silicon Controlled Rectifier a small current is applied to the gate circuit. Some people would say a small voltage. The SCR is a current driven device. So when enough current flows through the gate in reference to the voltage applied across the Anode and Cathode then the conduction from the Anode to the Cathode is switched having a very low resistance This is a uni-direction device. The triac is a bi-direction device. This does a good job in defining this function. https://en.wikipedia.org/wiki/Silico...lled_rectifier

This is why it is much easier if one has a schematic of the board.
So it the Compressor motor is good then this refrigerator is worth repairing.
How I believe your circuit is set up is the compressor has a start winding. When the voltage is applied to this winding the motor should begin to turn. As the voltage increased on this winding the motor turns faster. All this can happen very fast. Once the motor has reached a certain speed a switch should be made to connect the motor to the run circuit and the primary winding of the motor. So I would suspect that the PTC when it is closed will by-pass the run circuit and primary winding when it opens it disconnects the Start up circuit and the Start winding and connects the Run Circuit and the Run winding. With that said one does not necessary has to has a run circuit and a run capacitor. You might just have the run windings.

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

@keeney yes that's my understanding too but that circuit board with the triac still doesn't make sense because only those smd components underneath connect to the gate and they aren't linked back to the main control inside the fridge. So is the main 120v fed to the gate as well through the smd components as a trigger to turn on?

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

It looks like there are two large ports and two small ports that may have Male pins going to those port for control. Need to see how that module is connected to the mounting plate or what ever.
No wiring diagram on the back of the fridge?

Those two large ports are what the run capacitor connects to. Nothing goes into the two smaller ones. No diagram on the fridge that I could find.

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

@keeney yes that's my understanding too but that circuit board with the triac still doesn't make sense because only those smd components underneath connect to the gate and they aren't linked back to the main control inside the fridge. So is the main 120v fed to the gate as well through the smd components as a trigger to turn on?

I believe the main 120 volt connects to the defrost circuit. If the refrig is in defrost it will not apply 120 volt to the compressor. It takes 30 minutes for defrost. What is the number on the triac. We can look the specs up and find out real fast. What they can do with a gate circuit is put a resistor in the gate which lowers the voltage and current going to the gate and still have the 120 volts on the drain and source. These would be two parallel circuits where the resistor on the gate would be eating almost all the voltage.

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

I believe the main 120 volt connects to the defrost circuit. If the refrig is in defrost it will not apply 120 volt to the compressor. It takes 30 minutes for defrost. What is the number on the triac. We can look the specs up and find out real fast.

I'll have to look tomorrow but I did look it up before that's how I know it's a triac and the pins were (from left to right if looking at it head on) M1 M2 Gate

[R_J]

Re: Anyone have troubleshooting knowledge of refrigerators?

If you are getting 120 volts across the line and neutral on that box on the compressor and you here the bi-metal switch cut in and out I suspect the compressor is seized.

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

So do you have voltage going to the compressor motor? and what pins have the voltage? I am trying to understand which conditions are causing the motor not to run. Is it the start circuit or the run circuit. It is possible that RJ is correct if the coolant system had a leak then you would not have a warning.

[caphair]

Re: Anyone have troubleshooting knowledge of refrigerators?

When I probe with volt meter at the relay I get 40vac on one terminal that drops and 115vac on the other that doesn't change. Using the bottom terminal as the common keeping my negative lead in (using similar relay to show what I'm getting for voltage readings as I don't have a pic of mine)

[R_J]

Re: Anyone have troubleshooting knowledge of refrigerators?

You don't need a coolant leak for a compressor to fail, (it will still run without coolant) one shorted turn in the motor winding is all it takes for it to not start and overload. If you had a current clamp, you could use it to check the start up current.

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

When I probe with volt meter at the relay I get 40vac on one terminal that drops and 115vac on the other that doesn't change. Using the bottom terminal as the common keeping my negative lead in (using similar relay to show what I'm getting for voltage readings as I don't have a pic of mine)

So this explains the full operation of what is happening. Yes I believe you suspect of 40 volt is correct. That is that it is to low. It seems that big cap is indeed a run cap and that cap is shorted out when the motor is starting and then is open when running the short is the PTC. You can verify this by ohming the PTC to the cap.
http://tech.akom.net/archives/31-Get...-the-part.html

[keeney123]

Re: Anyone have troubleshooting knowledge of refrigerators?

You don't need a coolant leak for a compressor to fail, (it will still run without coolant) one shorted turn in the motor winding is all it takes for it to not start and overload. If you had a current clamp, you could use it to check the start up current.

If the coolant leaks then with the coolant there is oil that lubricates the compressor. With out that oil that compressor will not run long.

He has already done a Ohm test on the windings and they are fine.

[R_J]

Re: Anyone have troubleshooting knowledge of refrigerators?

I have a friend that uses a fridge compressor to evacuate auto air conditioning, the oil is in the compressor and as long as you don't turn it upside down the oil stays in the compressor. He has been using it for years without a problem.
Check the internet for "make a fridge compressor into a vacuum pump"

if the short is only a couple windings the dc resistance will not change by much but the motor will not run.

check the run cap. it could be open but if the bi-metal over currrent is tripping I suspect the rotor is locked