Hot Compressor after working for several days

[stelmo]

Hi Folks

Ive a problem with a Samsung fridge freezer, in that it will work perfectly for several days perhaps even a month but then you will notice that its no longer cold, feeling the compressor at this stage its very hot, where as when its working ok the compressor is cool.

I assume its a compressor issue?

Its an expensive 'american' style unit so I would like to get it back up and running again

It initially had a PTC replaced as it wasn't releasing the start circuit so it was constantly cycling the PTC and over stressing the compressor start winding - I'm wondering if that has damaged it?

[aramis]

Welcome to RE forums!

Yes, starting the compressor repeatedly and triping its protection can damage it.

If the start circuit is continiously energized it burns in the order of 20 seconds.

The problem may not be the compressor but refrigerant charge or plugged filter dryer or cap tube, or even faulty controls.

You can get information from several manufacturers, like:
http://www.embraco.com/DesktopModules/DownloadsAdmin/Arquivos/MP01EG.pdf

The best thing you can do is call a service to check the system.

[stelmo]

I'm an electrician, not a refrigeration engineer, I do like to further my learning so Id prefer to do this myself and keep costs down like I did with the PTC circuit.

So the compressor could be hot because the system is continually calling for cooling due to a clogged filter dryer perhaps?

[install monkey]

is it froze up??- is the sirflow good when you push the door switch in to start the interior fan, is the condenser coil clean?

[stelmo]

is it froze up??- is the sirflow good when you push the door switch in to start the interior fan, is the condenser coil clean?


Hi

Fans are working well, coil is clean

the compressor is almost too hot to touch when it gets to the point where the fridge is no longer cold

[install monkey]

blocked drier/capillary tube or compressor not pumping or loss of gas- any of these and your gonna have to get a fridggie out to furthur diagnose- is it under warranty?

[frank]

What gas is the fridge on?

[aramis]

I'm an electrician, not a refrigeration engineer, I do like to further my learning so Id prefer to do this myself and keep costs down like I did with the PTC circuit.

First try to get as much information on the compressor as you can, maybe someone can help if you post the compressor’s model number. Not all compressors have the model in the largest letters in their tag but should be somewhere.

One important piece of information now is the ohm resistance of the coils.


So the compressor could be hot because the system is continually calling for cooling due to a clogged filter dryer perhaps?

Yes, there are several causes for this and a visual inspection like Install Monkey is asking will shed some light, but you will probably need pressure gauges and a port to connect them.

Needless to say that just like you may electrocute there are several safety issues with pressurized systems and the refrigerants they use. Be careful, you may read about safety in these posts I’d suggest at least use safety goggles and long sleeve shirts.

[tonto33]

It be running on r134a you will need someone to put set of gauges on it to check how much refrigerant you got, then it fairly easy to sort out, you could put line tap on youself and buy can of r134a from likes of halfords and try refilling yourself but if got blockage hen you need engineer

[frank]

If it's on R134a then it's more than likely a blocked capillary due to oil flocking

[stelmo]

Its back on now and cooling as normal, but I know come a few days it will start again

Coil resistances are as normal

Its not under warranty

[install monkey]

also 2079 qualification would be of use,and a line tap valve

First try to get as much information on the compressor as you can, maybe someone can help if you post the compressor’s model number. Not all compressors have the model in the largest letters in their tag but should be somewhere.

One important piece of information now is the ohm resistance of the coils.



Yes, there are several causes for this and a visual inspection like Install Monkey is asking will shed some light, but you will probably need pressure gauges and a port to connect them.

Needless to say that just like you may electrocute there are several safety issues with pressurized systems and the refrigerants they use. Be careful, you may read about safety in these posts I’d suggest at least use safety goggles and long sleeve shirts.

[stelmo]

Its running on R600A, does that alter things?

[mikeref]

Does the compressor have a start capacitor?

[stelmo]

Does the compressor have a start capacitor?

Yes, piggy backed on the PTC

[mikeref]

Yes, piggy backed on the PTC And.. that tested o.k? Also, when cooling fails, is the compressor actually running, or attempting to start and fails.

[aramis]

R600a does bring in a new safety concern, all else is about the same.

It is a flammable refrigerant and Install Monkey rightfully points out you should have City and Guilds 2079 qualification … so I hope this is a job for yourself!

If this starts again the most probable cause is a refrigerant leak, don’t try to find it with match!

Leaks may also bring contaminants into the system, like air and water.

Water in the system may temporarily plug the capillary tube and produce the overheated compressor and lack of refrigeration. The system can work OK until water freezes and you have the problem again. This will make the compressor fail.

Especially dangerous in an R600a system is that you may have now air+fuel+heat (of compression) in the system and this is calling for trouble.

Please if you don’t want to do yourself a favor, do it for us and call a qualified service!

[stelmo]

And.. that tested o.k? Also, when cooling fails, is the compressor actually running, or attempting to start and fails.

Havent tested the capacitor
As I recall when it gets to the point of not cooling and the compressor is very hot, It wont start even manually

[aramis]

The internal protector probably tripped and you have to wait until it cools an resets. Cannot confirm this if you don't post compressor model.

[mikeref]

Havent tested the capacitor
As I recall when it gets to the point of not cooling and the compressor is very hot, It wont start even manually Change the capacitor. The uf number is on the capacitor. Cap testing is sometimes inaccurate. Good luck.

[aramis]

you should respect the capacitor minimum voltage too.

[stelmo]

The internal protector probably tripped and you have to wait until it cools an resets. Cannot confirm this if you don't post compressor model.

Compressor model is MK4A5Q-R1U

[aramis]

If it is external you’ll see it when you remove the plastic cover of the electric terminals.

model
voltage comp motor ASHRAE
cooling capacity efficiency
EFF COP EER
[V-Hz] cooling type Kcal/Hr Watt BTU/Hr Kcal/WHr W/W BTU/WHr
MK4A5Q-R1U 220-50 ST RSCR 222 258 881 1.4 1.63 5.56
240-50 222 258 881 1.38 1.6 5.48

It also says that the discharge temperature should never reach 100°C measured at 5cm from the body of the compressor but with insulation.

15.32cc power input @-23 154W so amps should be around 1 or little less at this temperature. When it starts can be much more but I can’t find tables I’d say around 2.5Amps.

The label should tell you the Locked Rotor Amps (LRA) just under the model name.

So measure amps with a fast response instrument if it is digital and if you get a reading near LRA, the compressor is stuck maybe broken maybe not.

If you read between 1Amp and 2.5A (approx.) and the protector trips it means the high temperatures are produced because of the working conditions and you’ll need a qualified service. You can try to measure the discharge temperature.

If the Amps are lower than LRA but much higher than 2.5, the problem may be the motor of the compressor and you’ll need to change it.

[stelmo]

Its been on for a few days now working fine, but it will stop again
Ill update when it does and do some tests

[aramis]

Other causes for overloading the compressor you can check are:

- Low voltage
- High voltage
- High thermal load (high temperature and high mass in the freezer)
- Dirty condenser
... or a combination of them!

[stelmo]

Well its still running ok, does that narrow down the possible causes?

I was thinking does the start capacitor have polarity protection?

[install monkey]

capacitors are not polarity sensitive
http://en.wikipedia.org/wiki/Capacitor

[stelmo]

capacitors are not polarity sensitive
http://en.wikipedia.org/wiki/Capacitor

They are, thats why I asked.
Electrolytic can fail if reversed, so I was checking to see if within the package there was some sort or protection.
or if start caps are of a different type

[aramis]

The capacitors used in RSCR (and many other) compressors are not electrolytic and so they don’t have polarity like Install Monkey says.

But they do have a terminal marked which indicates which plate is the closest to the metal casing. Unfortunately they are drawn in electric diagrams like an electrolytic capacitor.

This marked terminal should be connected to the active phase and the case to ground so that if the outer plate fails and shortcircuits to the casing, the capacitor will short to ground blowing the main fuses.

This way you’ll never have the outer casing of the capacitor connected to the active phase in failed capacitors. This would be very dangerous in installations without differentials.

Of course this protection was designed in a time when differentials were not standard protection.

[stelmo]

The capacitors used in RSCR (and many other) compressors are not electrolytic and so they don’t have polarity like Install Monkey says.

Thanks for that informative answer.
Install Monkey made it sound like he was suggesting capacitors in general didn't have polarity, the link was about all caps.

[install monkey]

with reference to the original post -quote it works perfectly for several days perhaps even a month-quote from 20th april- its been running for a few days now-thats around 2 weeks- you may not be out the woods yet.
id moniter the compressor current- shell temperature, and pipe temperatures-suction and discharge.test the actual capacitor microfarad value as it needs to be within 10% of the stated uf value.[
you also stated in post 18- that it wont even start manually- how were you trying to start it?
just trying to help identify your intermittant fault

Hi Folks

Ive a problem with a Samsung fridge freezer, in that it will work perfectly for several days perhaps even a month but then you will notice that its no longer cold, feeling the compressor at this stage its very hot, where as when its working ok the compressor is cool.

I assume its a compressor issue?

Its an expensive 'american' style unit so I would like to get it back up and running again

It initially had a PTC replaced as it wasn't releasing the start circuit so it was constantly cycling the PTC and over stressing the compressor start winding - I'm wondering if that has damaged it?

[aramis]

Well with the general use of electronics and DC control motors in refrigeration we will start to get used to electrolytic capacitors, that were present in electronic control boards so far, .... but we will never call them condensers! :)

[install monkey]

how much subcooling should i expeect off a 50uf cap- haha

Well with the general use of electronics and DC control motors in refrigeration we will start to get used to electrolytic capacitors, that were present in electronic control boards so far, .... but we will never call them condensers! :)

[mikeref]

Thanks for that informative answer.
Install Monkey made it sound like he was suggesting capacitors in general didn't have polarity, the link was about all caps. Capacitors for your fractional horsepower compressor are a dime a dozen and you can connect it this way or that. Wiring diagram will show -||- symbol.

[stelmo]

with reference to the original post -quote it works perfectly for several days perhaps even a month-quote from 20th april- its been running for a few days now-thats around 2 weeks- you may not be out the woods yet.

Oh it will fail I know that from the past occasions this has happened

[stelmo]

you also stated in post 18- that it wont even start manually- how were you trying to start it?

By applying power directly to the start winding manually for a second to start it

[aramis]

Stelmo as an electrician you should know how to test a capacitor with instruments.

If you don’t have instruments you can use the time constant method.

You can also record volts (and hopefully amps too) so you can rule out electrical problems.

If all electrical variables measure OK you may look for causes in the control, but several have posted here the most probable causes and they are in the refrigeration circuit.

Someone trained will diagnose it in short time, and you will be able to enjoy your R&R cold!

The instruments you need to buy to diagnose the system correctly cost more!

Plus it is safer … so: Go call a service!

[mikeref]

May i just add my Threepence worth here. Calling a fridgie when all is working well with your fridge, is not going to solve the problem ;).
This is like taking your car to the garage because of an intermittent fault with cruise control, or some rattle that just won't show up when the mechanic takes the vehicle for a test drive... been there... done that.:rolleyes:

Until the fault actually re-occurs constantly,then it would be very difficult for anyone to precisely diagnose the cause of your fridge problem.
That is why i am saying, swap out the compressor capacitor and give that a try. Any of the two wires can go to original cap placements on the relay, without any drama..Mike.

[install monkey]

id go 1 furthur and change the ptc relay the klixon is probably internal as its on r600-as both parts are cheap and may cure your predicament- otherwise the intermittant faul will rear its ugly head more frequently and then it would be easier to diagnose-but in the meantime id moniter running current,start current- test the windings -insulation-check any condenser fan isnt failing causing the overheat problem too

May i just add my Threepence worth here. Calling a fridgie when all is working well with your fridge, is not going to solve the problem ;).
This is like taking your car to the garage because of an intermittent fault with cruise control, or some rattle that just won't show up when the mechanic takes the vehicle for a test drive... been there... done that.:rolleyes:

Until the fault actually re-occurs constantly,then it would be very difficult for anyone to precisely diagnose the cause of your fridge problem.
That is why i am saying, swap out the compressor capacitor and give that a try. Any of the two wires can go to original cap placements on the relay, without any drama..Mike.

[stelmo]

Stelmo as an electrician you should know how to test a capacitor with instruments.


I never asked how to test a capacitor, my fluke metre can do it

[stelmo]

id go 1 furthur and change the ptc relay
The PTC relay was changed if you read my first post.

Install Monkey, we cant all be a smart arse and know everything. I am well aware that calling a refrigeration engineer would be the faster way to go. However it outweighs the cost of the fridge to me. Also where would we all be if we never learnt anything in life?

[stelmo]

That is why i am saying, swap out the compressor capacitor and give that a try. Any of the two wires can go to original cap placements on the relay, without any drama..Mike.

Thankyou for that, a new cap is on its way.

[install monkey]

believe me im no smart arse- theyre's a lot of members on here that can make me look simple on the other hand there are a few on here that make me look clever.
:o just trying to help diagnose the problem

The PTC relay was changed if you read my first post.

Install Monkey, we cant all be a smart arse and know everything. I am well aware that calling a refrigeration engineer would be the faster way to go. However it outweighs the cost of the fridge to me. Also where would we all be if we never learnt anything in life?

[stelmo]

OK failed again today, capacitor isn't at fault
compressor is very hot, so I assume its internal cut out has tripped and it makes a vibrating noise
switched off to cool down its now back on cooling fine!

[nike123]

If you measure start and run current and voltage, then we will knew lot more than now.
Than we will know if safety circuit is runnig ok or wrongly.
From that we can go further and diagnose systematically.