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Bosch B22CS50SNS 03 not cooling


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tweak_four17

Hello,

 

I have the Bosch B22CS50SNS 03 side by side fridge/freezer combo. A couple days ago I woke up to the freezer side of the display reading AL and a constant beeping. I silenced the alarm and discovered everything in my freezer was now thawed. I took the back panel off the fridge and saw the condenser was very dirty and dusty so I vaccumed it off hoping that would fix the problem but it does not. I called a repair man to come look at it and he pulled the back panel off and touched the compressor. He noted it was not warm and therefore was not likely to be trying to start and determined most likely the controller for the compressor was shot. I was quoted ~$600 to fix and replace this with only a 50% guarantee that it would fix the fridge and that it may be the compressor after all. I did a bit of digging online and found a YouTube video that sent me here. I pulled the inverter box off the compressor and checked the resistance across the windings, all are around 7.5 ohms but I could not get a stable reading (it would flicker from 6.9-8 mostly staying around 7.5). Not sure if my multimeter is just junky or if that is indicative of something. I tried to measure the input VDC to the inverter box but was unable to conclusively tell if I had done it correctly or not. There appears to be 2 wire harnesses above the inverter, one is the 120v input from the house into a block that appears to split to 2 other power inputs and the other was 3 wires, a ground plus 2 more. I assumed that was the VDC input being fed back from the motherboard on the top. Measuring there occasionally I would read 3V, or -0.3V or sometimes over range. Maybe I'm just doing a bad job, as I'm sure you can tell I am not really an electrical guy.

Just curious if anyone has an actual repair manual available for this unit or if anyone has any other ideas to test or if it does indeed sound like the controller (I assume he meant the inverter since he didn't even open the top portion of the fridge to look at the motherboard)..?

 

Thanks for your help and advice!

Tweak

 

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3-6 VDC is a good signal voltage for some inverters... If the tech never pulled out his meter and even checked as far as you did, I would disregard his diagnosis.

I will peruse the service manual tomorrow and see what I can dig up as far as specific voltages to test for...

As a grasshoppah, you won't be able to look at any diagrams or download the manual if I post them...

 

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tweak_four17

Thank you, I appreciate you looking into this. Too bad grasshoppah status impedes actually looking at anything though :/

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tweak_four17

Not sure if its allowed to post links to other forums or not (couldn't really find any rules..) but I did find a place on another forum saying that input voltage to a bosch inverter  is not unsual to be 2.4V, so maybe it is the inverter? Would just like to eliminate as much as possible as that inverter is a pricey little unit. 

Quote

I finally talked to an authorized Bosch repair tech to find out how much it would cost to have him take a look. He told me something that may be useful to other DIYers working on Bosch refrigerators; my 2.4 V DC to control signal to the inverter is a normal voltage level for Bosch.

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Richard Demint
On 7/10/2017 at 3:11 PM, tweak_four17 said:

Hello,

 

I have the Bosch B22CS50SNS 03 side by side fridge/freezer combo. A couple days ago I woke up to the freezer side of the display reading AL and a constant beeping. I silenced the alarm and discovered everything in my freezer was now thawed. I took the back panel off the fridge and saw the condenser was very dirty and dusty so I vaccumed it off hoping that would fix the problem but it does not. I called a repair man to come look at it and he pulled the back panel off and touched the compressor. He noted it was not warm and therefore was not likely to be trying to start and determined most likely the controller for the compressor was shot. I was quoted ~$600 to fix and replace this with only a 50% guarantee that it would fix the fridge and that it may be the compressor after all. I did a bit of digging online and found a YouTube video that sent me here. I pulled the inverter box off the compressor and checked the resistance across the windings, all are around 7.5 ohms but I could not get a stable reading (it would flicker from 6.9-8 mostly staying around 7.5). Not sure if my multimeter is just junky or if that is indicative of something. I tried to measure the input VDC to the inverter box but was unable to conclusively tell if I had done it correctly or not. There appears to be 2 wire harnesses above the inverter, one is the 120v input from the house into a block that appears to split to 2 other power inputs and the other was 3 wires, a ground plus 2 more. I assumed that was the VDC input being fed back from the motherboard on the top. Measuring there occasionally I would read 3V, or -0.3V or sometimes over range. Maybe I'm just doing a bad job, as I'm sure you can tell I am not really an electrical guy.

Just curious if anyone has an actual repair manual available for this unit or if anyone has any other ideas to test or if it does indeed sound like the controller (I assume he meant the inverter since he didn't even open the top portion of the fridge to look at the motherboard)..?

 

Thanks for your help and advice!

Tweak

 

 if just a touch with my hand could diagnose everything. Unplug unit for a least 5 minutes, plug back in and with back already off either listen or feel for compressor to come on, could take a  minute and also may start off real slow. Did you have your 120volts to inverter board when you checked?

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tweak_four17

I've done that a couple times, when I power it back up I can hear it go through some checks with the ice maker. There is a clicking sound coming from the motherboard. The condenser fan kicks on but the compressor does not appear to start. I did my checks while the power was plugged in for sure when I was getting the 3V, now I'm not sure about the rest. I also used a meter to test for continuity to try and see where the smaller wire harness goes to the motherboard but was never able to read any voltage up on top.

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Richard Demint
16 hours ago, tweak_four17 said:

I've done that a couple times, when I power it back up I can hear it go through some checks with the ice maker. There is a clicking sound coming from the motherboard. The condenser fan kicks on but the compressor does not appear to start. I did my checks while the power was plugged in for sure when I was getting the 3V, now I'm not sure about the rest. I also used a meter to test for continuity to try and see where the smaller wire harness goes to the motherboard but was never able to read any voltage up on top.

Need to check for 120volts (2 wire plug) going from main control board to inverter board on compressor. Also Unplug unit from wall, go to every plug in and unplug, inspect both sides of plug and reinsert. On the inverter board you will have to take plastic cover apart to get to plugs. If you have 120 volts at inverter board and still no compressor run, replace inverter board.

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tweak_four17

Ok thank you, I will give that a shot tonight when I get home from work. You are saying the 2 wire plug from the main control board to the inverter board is inside the inverter and to test it I need to take the cover off or are you referring to 2 different places to test?

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Richard Demint
3 minutes ago, tweak_four17 said:

Ok thank you, I will give that a shot tonight when I get home from work. You are saying the 2 wire plug from the main control board to the inverter board is inside the inverter and to test it I need to take the cover off or are you referring to 2 different places to test?

You can test at main board but even if you have 120 volts there you want to make sure it is getting to that inverter board. Not getting 120 volts at main board= main board issue. getting 120 volts at inverter board=inverter issues. I would strongly suggest you try the unplugging, inspecting and reinserting first. If you do not feel comfortable with checking voltages, STOP! Do not take apart inverter box while unit is plugged in!

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tweak_four17

So to check the inverter are you suggesting unplug the fridge, take the cover off to expose the terminals and then plugging the fridge back in to test?

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To properly dignose the inverter board, it does need 120V, but it also needs signal voltage from the main board- this is how it "knows" what speed to run the compressor at...

4.3 Self-Diagnosis-Mode (SDM) Start program

Switch the appliance off and on again.

Press the “select” and “options” simultaneously for 5 s until the display shows “L0”.

The system checks all electrical components automatically.

End program When testing is finished, it quits automatically.

 

Let me know if it displays any codes...

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tweak_four17

I'm not at the unit at this moment, but I think I tried that (assuming the buttons are the 2 on the left of the display). It runs from L0 to L15 or so and then boots back to the normal display. Would it freeze at the error or will it just continue on and drop back to the display if I'm not paying attention?

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Richard Demint
24 minutes ago, tweak_four17 said:

So to check the inverter are you suggesting unplug the fridge, take the cover off to expose the terminals and then plugging the fridge back in to test?

I would strongly suggest you try the unplugging, inspecting and reinserting first. Yes unplug the unit when ever you are removing electrical components.

 

 

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Richard Demint
18 hours ago, Richard Demint said:

 if just a touch with my hand could diagnose everything. Unplug unit for a least 5 minutes, plug back in and with back already off either listen or feel for compressor to come on, could take a  minute and also may start off real slow. Did you have your 120volts to inverter board when you checked?

For the manual on here you will need to become a member, all units come with a tech sheet located in various places like under the fridge,sticker on back of unit, toe kick panel,under door hinges ect. Sometimes (techs) do not put them back but worth the look.

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tweak_four17

To the best of my knowledge the repairman who looked at it this week was the only one to ever do that and he didn't take it so I will poke around and see if I can find anything stashed away,

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1 hour ago, Hiroshi said:

The system checks all electrical components automatically.

End program When testing is finished, it quits automatically.

 

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tweak_four17

So if it did generate an Error on say, L4, it would flash on then continue to L5 and if I wasn't paying close attention to it I'd miss it? I'll have to pay more attention next time. I just figured it would pause or give some notification at the end that it had an error lol.

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tweak_four17

Ooook. I took apart every connection on the back panel and every connection on the board found on the top right on the unit. Everything looks fine. Plugged it in and ran the self test, counts from L1 to L15 and does not generate any noticeable error before dropping back to the main display. Took the cover off the inverter box and have 120V at the power connection and 2.5VDC at the control connection when it is plugged in. Tested the resistance across the compressor windings again but sitll was getting an unstable number between 6.5 and 8ohm but more often than not roughly 7.5ohm (meter error? its hard to get the little probes in there). At this point I'm kind of leaning towards the inverter box, but is there a way to easily test its output to confirm its not the compressor? I put the fridge into service mode using a manual I found for a slightly different model (B22CS80SNS; 80 instead of 50) and was able to test drive fans and temp sensors but was unable to force a compressor start. Probably not conclusive as I'd imagine if either the inverter box or the compressor was shot that it wouldn't start. According to the manual I have L15 of the self diagnostic mode should be a compressor test, but since it fails to start I'm not sure why no error is generated..I'd really like to have some confidence in this before I buy some new parts as the inverter box comes out to just under $500 canadian. Bit pricey.

Thanks again for your time and help!

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On an inverter compressor, the ohm measurements between any combination of the three pins should be equal. 6-8 ohms is a normal value for compressor windings in general, so the only other thing I would do is test for continuity from each pin to the metal body of the compressor to ensure it is not shorted to ground.

Fancy machines have fancy-priced parts.

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Richard Demint
14 hours ago, tweak_four17 said:

Ooook. I took apart every connection on the back panel and every connection on the board found on the top right on the unit. Everything looks fine. Plugged it in and ran the self test, counts from L1 to L15 and does not generate any noticeable error before dropping back to the main display. Took the cover off the inverter box and have 120V at the power connection and 2.5VDC at the control connection when it is plugged in. Tested the resistance across the compressor windings again but sitll was getting an unstable number between 6.5 and 8ohm but more often than not roughly 7.5ohm (meter error? its hard to get the little probes in there). At this point I'm kind of leaning towards the inverter box, but is there a way to easily test its output to confirm its not the compressor? I put the fridge into service mode using a manual I found for a slightly different model (B22CS80SNS; 80 instead of 50) and was able to test drive fans and temp sensors but was unable to force a compressor start. Probably not conclusive as I'd imagine if either the inverter box or the compressor was shot that it wouldn't start. According to the manual I have L15 of the self diagnostic mode should be a compressor test, but since it fails to start I'm not sure why no error is generated..I'd really like to have some confidence in this before I buy some new parts as the inverter box comes out to just under $500 canadian. Bit pricey.

Thanks again for your time and help!

There should be no fluctuation between compressor pins. All should be exactly the same even 1ohm off it will not work.

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Richard Demint
14 hours ago, tweak_four17 said:

Ooook. I took apart every connection on the back panel and every connection on the board found on the top right on the unit. Everything looks fine. Plugged it in and ran the self test, counts from L1 to L15 and does not generate any noticeable error before dropping back to the main display. Took the cover off the inverter box and have 120V at the power connection and 2.5VDC at the control connection when it is plugged in. Tested the resistance across the compressor windings again but sitll was getting an unstable number between 6.5 and 8ohm but more often than not roughly 7.5ohm (meter error? its hard to get the little probes in there). At this point I'm kind of leaning towards the inverter box, but is there a way to easily test its output to confirm its not the compressor? I put the fridge into service mode using a manual I found for a slightly different model (B22CS80SNS; 80 instead of 50) and was able to test drive fans and temp sensors but was unable to force a compressor start. Probably not conclusive as I'd imagine if either the inverter box or the compressor was shot that it wouldn't start. According to the manual I have L15 of the self diagnostic mode should be a compressor test, but since it fails to start I'm not sure why no error is generated..I'd really like to have some confidence in this before I buy some new parts as the inverter box comes out to just under $500 canadian. Bit pricey.

Thanks again for your time and help!

Inverter Compressor Systems

Although inverter compressors do the exact same thing as the old skool compressors-- pump refrigerant vapor-- and they physically move the vapor the same way-- through a vapor-compression cycle-- they are powered and controlled very differently.

For one thing, inverter compressors use a special three-phase voltage produced by a special control board called an inverter. Fuggetabout 120 VAC, 60 Hz line voltage. We're not in Kansas anymore, boys and girls! Both the amplitude (amount) and frequency of the input voltage will vary. Typical specs are 80 to 230 VAC with the frequency ranging anywhere from 57 to 104 Hz. The higher the frequency, the faster the inverter compressor will run.

So, inverter compressors, unlike their old skool forebearers, really can work harder. In fact, this is exactly why the manufacturers are using these inverter compressor systems; they can match how hard the compressor needs to work to the actual refrigeration work needed to keep the beer cold. By doing it this way, the compressor draws less power and the manufacturers can meet the Energy Star requirements.

Inverter compressors have three windings, not just two like the old skool units. All three windings should have the exact same resistance. If the resistances vary from each other by as much as a 1 ohm, the compressor will not run correctly. In fact, this is one of the ways of checking an inverter compressor: making sure that all three windings have the exact same resistance. Check the manufacturer's spec for what that exact resistance reading should be. This is different from the old skool compressors with just two windings and the start winding has a much higher resistance than the run winding.

Remember how a common troubleshooting trick with the old skool compressors is to power it directly with a test cord and see if it starts? Don't try that on these inverter compressors because you'll permanently break it. If you're a professional Appliantologist and you do this on a service call, you just bought your customer a new refrigerator!

Let's summarize the inverter compressors:

- have three windings, not just two; all three windings have the exact same resistance

- does not use a start relay/overload device

- runs off a special voltage produced by an inverter board; the voltage varies in both magnitude and frequency: the higher the frequency, the faster the compressor runs

- variable capacity, variable speed

- cannot directly power the compressor (well, you could but you'd regret it)

Troubleshooting Inverter Compressor Systems

If you're working on an inverter compressor system where the compressor isn't running, you can't power an inverter compressor directly to test it. But you can (and should!) check the resistances in all three windings to rule out an open winding. If the compressor windings check good, this is not diagnostically conclusive that the compressor itself is good. But if, OTOH, the winding resistances are imbalanced or one of them is open, this is diagnostically conclusive that the compressor is bad.

Okay, so let's say the compressor windings check good but it's not running. Now what?

Now you have to check the inverter board itself. There are two different tests you can do on the inverter board to see if it's good or not:

1. Check for good input voltages.

An Inverter board will have two different input voltages:

- 120 VAC main power supply

- 4 to 6 VDC control voltage from the main control board (or Muthaboard-- a completely separate circuit board in the refrigerator)

If you're missing one of these voltages, the inverter board can't run the compressor. You'll need to backtrack and find the missing voltage. Could be a bad wire harness connector, bad muthaboard, etc. BTW, make all voltage measurements with everything CONNECTED. Otherwise, you'll get different readings that could be misleading.

OTOH, if you're getting both of these input voltages to the inverter and the compressor isn't running (and you've already checked the compressor winding resistances), then you need to do this next test:

2. Check the current draw on the 120 VAC power supply.

- Disconnect the 120 VAC power supply from the inverter board.

- Connect your amp meter around one of the wires supplying 120 VAC to the inverter board (doesn't matter which one).

- Reconnect the 120 VAC power supply to the inverter board and watch your amp meter.

If the meter stays at 0 amps, the inverter board is toast-- it's not even trying to start the compressor.

If you see the current draw jump to say 4 amps (typical LR current in these inverter compressors) and then drop off, keep watching. Most inverter boards will repeatedly try to power up the compressor. On GE refrigerators, for example, the inverter will try to start the compressor 12 consecutive times. If the compressor fails to start, the inverter will timeout for 8 minutes and then try again. Other manufacturers may have different test schemes but the idea is the same: if the inverter is working properly, you'll see activity on your amp meter as the inverter tries to do its job.

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Just to follow up and close this thread out in case anyone else has a similar issue. I bit the bullet and bought the new inverter box. 10 minute install and boom, fridge was running like new. Thanks for you help!!

 

 

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