Samsung double door fridge overload relay changed 3 times in 2 weeks

[Vas786]

TL;DR

Samsung double door fridge overload relay changed 3 times in 1 week

Hi Guys, I am new to this forum. I request an expert opinion cause I've not found anything relevant on the web search.

I have a Samsung double door refrigerator. Two weeks ago, it stopped cooling and clicking noise coming from the overload relay box plugged into the compressor. I took out the relay overload unit and opened it. I found thermistor disc in pieces. I bought a new unit along with new capacitor from parts store and fridge working fine for 4 days.

It stopped cooling again and clicking noise. I changed it 2nd time which lasted 3 days and then 3rd time(lasted 2 days). I checked compressor readings. They seems to be ok(7, 10, 17). I started compressor with no relay(with overload plugged in) 4 or 5 times to use the food in the fridge. Every time I started the compressor without a relay , the overload switched off when it was cool enough. I don't want to start it too many times resulting in compressor damage. I am suspicious that something else is faulty causing the thermistor disc in the relay unit to melt and fail.

Other observations: Fridge voltage stabilizer output voltage is 210 volts. Voltage going to compressor through relay unit is also 210 volts. Fan in the freezer unit is running and blowing cold air when compressor is started with or without relay. Ice is formed in the ice tray. Only other observation, ice is forming in the tray only just in a couple of hours.

Any help is highly appreciated.
Thank you very much,
Kind regards,

 

[Vas786]

Forgot to mention, there is no short to the body of compressor from any of the 3 pins(start, run or common). The supply voltage is between 200 to 270v Thank you

 

[Bystander]

Where are you located? How long have you had the unit? Have you had anyone look at the "power factor/line load" for the unit?

 

[DaveE]

If the thermistor is the part that is repeatedly failing (you didn't really say what you found after the first one), then the problem is most likely the components downstream causing that failure. The thermistor's job is to limit the current surge at turn-on by being resistive until it heats up. So, heat is guaranteed to be present; too much heat is by far the most likely failure mode. Too much heat for the thermistor happens when the downstream load doesn't reduce it's current at turn-on quickly enough. Like, for example, a compressor motor that starts slowly or has other faults causing higher than normal current. Of course, it is most likely to be the largest devices in terms of power requirements that will cause this excessive current at turn-on.

 

[sophiecentaur]

If you are in the UK it may be worth while contacting UKWhiteGoods. They are a spares supplier and have a forum plus a guy (Dave, iirc, who is Scots and has an encyclopaedia for a brain) who will give very good advice from his extensive knowledge. I had a Hotpoint Fridge Freezer and it was behaving stupidly. He told me to change 'both' thermistors, despite only one of them appearing faulty. Bingo - and then about fifteen years of faultless running.
Many of the UKWG forum users are in the business and they are good at telling you the most likely solution. That's not always satisfactory from the PF point of view (we always want an answer to the why why why? question) but 'valve changing' on old tellys was a tried and tested method.
There will be an equivalent forum in all countries, I expect.

 

[DaveE]

Many of the UKWG forum users are in the business

Unlike us, LOL. This is great advice.

 

[Vas786]

@DaveE
Thank you very much for the reply. I opened the relay when it failed 2nd and 3rd time and found the thermistor disc in pieces .But this failure is not happening with one start. Room temperature here is around 40 degrees celsius. It is happening after around 20 start and stop cycles. How to check whether compressor is the problem?. The resistance readings seems to be ok and it is starting after replacing relay (thermister) and also without relay by momentary shorting of start and run windings with no problems. As I already mentioned, the water in the ice tray is freezing quickly in matter of couple of hours from room temperature of around 40 C which is bit unusual. Can this be a thermostat/evaporator fan problem? This fridge freezer is 10 years old, no digital controls, with manual disc controls for temperature both in freezer and fridge compartments. The Fridge is used at same location since brand new.

 

[Lnewqban]

How is the Amps consumed while normally running versus nameplate value?

 

[sophiecentaur]

How is the Amps consumed while normally running versus nameplate value?

Start current on fridges is well known to be very high. Even a 'modest spec' unit can cause the lights to dim when the compressor starts in some houses.

The OP needs a Refrigeration Problems Forum to get the low down on this particular model. How many fridges have you, I or other PF members had to trouble shoot? That's what counts with a modern fridge.

 

[Averagesupernova]

I have yet to have a fridge fail in a manner other than runs constantly and doesn't cool.

 

[sophiecentaur]

I have yet to have a fridge fail in a manner other than runs constantly and doesn't cool.

Also:
Defrost element in cooling panel runs constantly and cooks the food.
Heat exchanger in 'frost free' freezer clogs up with ice and needs (for hours) manual defrosting. (mine and mother in law's)
Door seal (irreplaceable) with hairline gap causes major water buildup.

And now, the OP overload problem rears its ugly head.

 

[Guineafowl]

Could the thermostat be the problem? There’s meant to be some hysteresis in the setting, eg cut-in at 6degC, cut-out at 2degC, to maintain a target of 4degC.

If that hysteresis is lost, the fridge will short-cycle, and keep switching on and off too quickly. If it switches on too soon, the compressor will have a hard tine starting against the residual pressure in the cooling system, resulting in a locked rotor start. This will heat stress the overload.

Also, if the fridge is rated for 230V nominal input voltage, then it will draw extra current at 210V, worsening the heat stress.

 

[Vas786]

Thank you very much. I will check thermostat