FIXED Whirlpool W8RXEGMWB00 Intermittently Not Cooling - Compressor? Inverter? Thermostat? Control Board?

[jethrodesign]

Model Number

W8RXEGMWB00

Brand

Whirlpool

Age

More than 10 years

Hi, our freezer has been Intermittently stopping cooling after working fine for a while (day or two). Sometimes unplugging it overnight will allow it to start working again, although this is not the case today. The refrigerator is 12-years-old.

NOTES:
- The condenser fan and evaporator fan both work fine, and are often running when it's not cooling.

- I now can feel around back to the Compressor, and it's not running when cooling stops (though other fans are).

- Condenser coils are clean now (they had been fairly covered in dirt).

- Evaporator coils look great, no uneven ice/frost.

- We had a service tech come look at it, but he just glanced at everything and said it all looked fine (of course it was working properly when he showed up). He thought it might be Defrost Control Board.

- We replaced the Defrost Control Board at the top of the refrigerator. Didn't help.

- When we turn the thermostat control in fridge to 'Off', all fans stop. Turning it back on causes fans to turn back on, but not Compressor.

- When the Compressor DOES come on, it cools really well (freezer = - 5° to 15°; fridge = 36° to 44°).

- We don't hear a 'clicking' sound I've heard mentioned of the Compressor trying to start.

QUESTIONS:

A) Do compressors generally either work or not work, or can they be intermittent like this?

B) If the thermostat was not working properly, would it cause BOTH the fans AND the Compressor to not turn on, or could it only affect the Compressor?

C) Does our refrigerator have a 'Main Control Board (ie, motherboard)' that's different from the Defrost Control Board we already replaced? Can't seem to find the part anywhere.

D) What tests should we run? Getting a multimeter today.

Thanks for any insight here! We're limited to a 28" wide refrigerator in our space, so from what I can tell that limits us to one of two refrigerators right now - a GE or a Whirlpool. Neither get stunning reviews for longevity, and none are in stock anywhere. So before spending $1k, want to see if ours can be salvaged. It's in great condition otherwise.

 

[Jake]

Yes, You have the invertor box on your model. It could be starting to fail on you.

You won't have any voltage with the inverter off of the compressor. The only way you can test an inverter is when it's on the compressor.

First Unplug the refrigerator from the wall outlet, then you can check the compressor while the invertor box is off the compressor. Touch your meter leads to any two pins. You should have 9-10 ohms. Install the inverter back on the compressor and plug it in. Give it a minute to enter cooling mode. At the inverter you should have 120 Volts AC between the black wire and the white wire.

Look for a red wire and a red and white wire. Don't disconnect anything. You should have between 3 and 6 Volts DC.

Here's the invertor box for your model you can order, if needed:
WPW10233421 Invrtr-Box


Jake

 

[jethrodesign]

Hi Jake, thank you so much for responding with helpful direction!

So, just to clarify, I need to test the A/C and control voltages coming IN to the inverter (not going from inverter to Compressor), correct?

And i need to get the meter leads into the connectors somehow while everything is still connected and running, correct?

I'll try to do that, along with checking continuity on the Compressor itself and report back.

Thanks!

 

[jethrodesign]

OK. I tried to do some initial testing tonight. I'm still a bit new to testing with the multimeter, so may need additional guidance.

RESULTS:
- Compressor:
All pin combos measure 6.3ohm.
Any pin to ground = 0L

- Control signal input:
There was only a single red wire coming in to inverter. I unplugged connector and ran meter inline to each connector end (is this correct method?).
Running = 53.3v
Off (thermostat turned off) = 1.01v

- A/C input:
I'm not sure how I would measure this with everything connected?!? The connectors have a mesh tape around them, so they're pretty insulated. And no room I can see to insert leads. So I unplugged connector and it measured 121.1v (when on or off).

QUESTIONS:
E) Does everything look correct and point fairly definitively to Inverter? $240 is just a lot if it doesn't fix the problem (unless any places would allow a return after connecting/testing if kept in good condition).

F) Is the Defrost Control Board I purchased (see attached photo) what is sometimes referred to as a 'Main Control Board', and what would be sending control voltage to inverter? Was under impression originally that this just controlled timing of defrost cycle.
I tried plugging the old one back in (as I think I can still return the new one), and the control voltage measured the same 53.3v when turned on. Wondering if the old one was OK after all.

THANKS FOR ANY INSIGHT HERE!!

 

[Jake]

See that's the problem, I've never seen a inverter box on a Whirlpool that's connected to the defrost board, that's very weird, so I have no clue on this one how that defrost board can provide DC volts to the 2 smaller wires.

I can ask Rick, maybe he has seen this setup before.

Jake

 

[jethrodesign]

Hi, thank you. It seems a lot on this fridge is not 'typical'. I see examples on the internet of a Main Control Board (or motherboard) under a panel on the back or something on a lot of refrigerators. But mine has no such feature that I can find.

And most of the examples I've seen seem to indicate a control voltage of 1-6v or so, but mine measured 53v. Did I possibly do the measurement wrong (in series between the connectors)?

I wish I could find an expert who is familiar with my fridge. But the last experience with having someone come out was completely useless and lost me $70. I'm open to suggestions...

I'm case it's helpful, I've attached a couple pics of the inverter & connections.

Thanks again for any help here!

 

[Jake]

Take the voltage readings from the inverter box electrical connections.

Jake

 

[Jake]

At the inverter you should have 120 Volts AC between the black wire and the white wire.

red wire and a red and white wire. Don't disconnect anything. You should have between 3 and 6 Volts DC.

Since I don't see a red/white wire on yours use the green ground wire as the other connector to check DC volts from, with that red wire I do see in your photo.

 

[jethrodesign]

Take the voltage readings from the inverter box electrical connections.

OK. But if the inverter needs to still be connected to the Compressor when taking the readings, I'm not sure how I'll get the leads onto the connections, which are partially inside the gray plastic box. The connector to the Compressor is very short, so not much space to work with. But I'll try...

 

[Jake]

Use this trick:

 

[jethrodesign]

OK. Sorry I'm such a newbie with the meter. I tried to take a reading from the control signal connector at the inverter to the end of the ground wire. I've attached 4 photos showing how I did this.

Photo 1 - shows how I connected the meter. I shoved a pin up into the connector at the inverter. Then touched this with one lead, and clipped the other onto the point where the ground wire connects.

Photo 2 - shows the reading when turned on. It measures 120v A/C! Tried this many times. Could not get ANY reading for D/C voltage, only A/C.

Photo 3 - shows the reading when off. 3v A/C.

Photo 4 - shows what the connector pins look like. There are 2 pins even though there is only 1 wire in the connector.

I don't know WHAT to make of this. From what I've read, I'm expecting 4-6v D/C for a 'control signal'. The only way to get a D/C reading is to insert the meter in series between the 2 connectors where you can disconnect device from input line. That still measures 53v D/C.

The power supply connectors at the inverter do measure 121v A/C whether the fridge is on or off (using thermostat).

Someone has to understand how this SHOULD work. My fridge wasn't that obscure when I got it. Prob an inexpensive Home Depot purchase 12 years ago.

I did note on some material from Embraco that their inverters have 1 of 2 different types of control modes - drop-in or frequency. And when replacing, you have to use one of same mode. Mine is a 'drop-in' type.

- Anyone know what a 'drop-in' type inverter is and if this helps to make sense of what I'm seeing??

Thanks again! Desperate for a working refrigerator, as ordering out every night is inconvenient and getting expensive.

 

[Jake]

Ok, I have no clue, you will need to wait for Rick to come back, he is under the weather, or go refrigerator shopping, the average life of refrigerators now is only 8-12 years, so yours is at the end of life.

Jake

 

[jethrodesign]

I just wanted to add some info that I found on an old post for someone with my refrigerator and what sounds like similar issues [ View what PJMax says in a couple posts here ].

He states (IF accurate) that:

The red wire to the inverter board is the trigger line. White to the inverter is neutral, black is 120v and the red is 120v when the stat is demanding cooling (when the fans are running).
You test the red by checking from the red wire to ground (cabinet). It should be present when the stat is calling for cooling and 0v when the stat is off.

IF this is correct information, it seems to confirm that my measurement of 120v A/C when testing between the red wire and ground 'might' be correct & good.

The wiring diagram he posted, again IF correct, also appears to show a pretty simple solution with just the thermostat sending the voltage to the inverter, and possibly the evaporator & compressor fans as well. If this is accurate, and I'm understanding it properly, it 'seems' like if the thermostat was not working properly, the fans would also not turn on (not just the compressor failing to turn on). But the fans seem to always turn on/off OK depending on cooling, and once it gets warm enough they run continuously unless I turn the thermostat to the OFF position.

 

[jethrodesign]

I was thinking this was just confirming I may have proper voltage coming IN to the inverter. But there's no easy way to tell if inverter is then sending proper signal/voltage on to the Compressor, right? To rule out the inverter being the bad part??

Ugh, wish it was easier to fully test/diagnose these things without having to purchase an expensive, non-refundable part...

And I do continue to shop for new refrigerators. Our space just limits us to 2 models (28" Whirlpool or GE from what I can find). And both seem pretty cheaply made when viewing floor models, are on backorder, and would be close to $1k when all is said & done. Hence my efforts to completely rule out my current fridge first...

 

[Jake]

When the compressor is NOT running and the condenser fan is running, then check the voltage at the inverter to see if its still getting power at 120 volts.

Jake

 

[jethrodesign]

OK. I did some more testing today to just make sure all is consistent and listed in one place. This time I tried to measure current to the inverter for the first time.

Here's what I've found. (Note: On or Off state is determined by turning thermostat in fridge on/off.)

INVERTER AC INPUT VOLTAGE
(measured at connectors of black & white wires) :
On - 120v AC
Off - 120v AC

INVERTER CONTROL VOLTAGE
(measured at single red wire connection & green ground) :
On - 120v AC
Off - 3v AC

INVERTER AC INPUT CURRENT
(measured with meter inserted inline/series with one of black or white wires) :
On - 0.02A
Off - 0.02A

----------------------

So, according to what I found here, would the fact that the inverter 'appears' to be receiving proper voltage (would still like someone to confirm my control voltage reading), but does not appear to be drawing any current, lead to the conclusion that the inverter is not even trying to fire up the Compressor?

- Are there possibly any places/people you can send an inverter into to test definitively if it's good or bad?

Thanks again for any insight! Trying to become a refrigerator and electrical testing expert in a couple weeks has been pretty challenging. If replacement refrigerator options were better, or replacement parts could be returned if not the fix, I could have probably figured this out long ago...

 

[Jake]

Like I mentioned above--->At the inverter you should have 120 Volts AC between the black wire and the white wire. If so and the compressor is not running but the condenser fan is running, then the compressor is the problem.

Jake

 

[jethrodesign]

Thanks for the continued help here! Much appreciated.

Like I mentioned above--->At the inverter you should have 120 Volts AC between the black wire and the white wire. If so and the compressor is not running but the condenser fan is running, then the compressor is the problem.

So just out of curiosity, I disconnected the black/white wires from the inverter (so taking inverter & Compressor out of the equation) and measured the incoming AC voltage. Those incoming lines still measure 120v AC whether fridge is on or off (condenser fan follows on/off state).

So if those lines would always measure 120v coming in, even if completely separated from inverter/Compressor, how would you properly rule out the inverter being the bad part (meaning it is not converting & passing the power on to the Compressor)?

From what I was reading elsewhere the only other test that might give insight is checking the resistance across the 3 pins on the Compressor, which mine passes perfectly.

Sorry, really trying to understand well what is going on and should be expected before deciding whether to try spending $240+ on an inverter, or just throwing the refrigerator away.

 

[Jake]

So if those lines would always measure 120v coming in, even if completely separated from inverter/Compressor, how would you properly rule out the inverter being the bad part (meaning it is not converting & passing the power on to the Compressor)?

From what I was reading elsewhere the only other test that might give insight is checking the resistance across the 3 pins on the Compressor, which mine passes perfectly.

Sorry, really trying to understand well what is going on and should be expected before deciding whether to try spending $240+ on an inverter, or just throwing the refrigerator away.

That's what I don't know, yours is much different than other models, that's why I asked Rick, but Rick has been sick for 2 weeks and I don't know when he's coming back.

I'm not going to be able to assist you anymore till he comes back, sorry.

Jake

 

[jethrodesign]

I just wanted to update this thread with a little more information I've received in case it helps confirm anything and for anyone else who may have a similar inverter/compressor setup to mine. I had reached out to the manufacturer of the inverter & compressor - Embraco - and they sent me some technical manuals. A fair amount of it is still a bit over my head, but I'm able to piece together some insight.

Frequency vs. Drop-in Control Modes:
It appears, at least with Embraco inverters, that there are 2 different main types of control signal modes they can work in - Frequency or Drop-in. Here's what I've taken from reading the tech sheets:
Frequency:
I believe this must be the more common type of inverter that most are familiar with. It has 2 control wires coming in for '+' and '-'.

From Embraco: "This option is used when the application uses an electronic thermostat, that controls the compressor speed through a frequency signal sent to the Inverter. The frequency signal is a digital square wave, with 0 to +5V voltage amplitude and defined range as described ahead. Compressor speed will follow the frequency signal, according to the relation described bellow (they show a graph comparing the input frequency from about 50-150Hz causing a compressor RPM of about 1500-4500)."

Drop-in:
This is the type of inverter my fridge has. It has (1) single control wire coming in (red in my case). This appears to be coming through the thermostat on the hot/phase wire, so this is probably why it measures 120v AC when the thermostat is ON.
This same feed appears to also be connected to the Evaporator and Condenser fans. So with my fridge, I believe that when the thermostat is ON, both the fans AND the compressor should be ON at all times (compressor speed being controlled by inverter board internally). And when it is OFF, both fans and compressor turn OFF. My fans turn on/off just fine with thermostat, just not the compressor.

From Embraco: " On this VCC mode, the command to switch on and switch off the compressor must be performed by the system’s thermostat, and the inverter, according to the system demand, does the speed control. The target is to achieve the minimum suitable speed, which is still enough to sustain the thermal load of the system, reducing the power consumption of the system.
The thermostat is connected to the Inverter through the Control Input Connection, using the Control Input Cable. Use the GND pin to connect the Thermostat with the AC power supply phase.

--------------------------------

So if I'm understanding everything correctly (if), then my system is actually a bit simpler than most inverter + compressor systems. The basic thermostat just turns everything on or off together based on temperature.

- I'd still love for someone with more knowledge or experience to confirm my assumptions here.

- And the tech manual troubleshooting describes 2 scenarios where the compressor might be bad:
A) Open compressor motor windings, which I think is tested by measuring resistance across compressor pins (mine seems to measure good here);
B) Compressor with locked rotor (due to mechanical damage).

- How would I know if the compressor had a locked rotor, or some other issue not revealed by testing the pins?

Since my inverter appears to be receiving the proper signals and voltages from what I can ascertain, it's either faulty and not turning compressor on (most likely), or it's fine but compressor is bad...