Kiour controller, compressor on for a second then off

[KBSOL]

Hello

We have a fridge at work with a kiour controller (REF-DF-SM) which is switching the compressor on for 1 second when the temperature rises to the setpoint, but operates normally when the temperature reaches 2 degrees above the setpoint.

This is what it used to do:
Setpoint at 5
Fridge temperature rises slowly and as soon as the temperature reaches 7, compressor comes on and switches off at 4. Doesnt switch on between these values. The cycle repeats.

Now it operates the same way but when the temperature rises from 4 to 5 it switches the compressor on for a second and then goes off. Compressor comes on as normal at 7.

I brought the setpoint down a degree to 4 so it cuts out when the fridge reaches 3 but it still started the compressor for a second when the temperature reached 4 so it must be linked to the setpoint.

I have occasionally observed the controller leave the compressor on to bring the temperature down 1 degree instead of being on for a second and then off.

Interestingly this problem only started after the compressor leaked and the system refilled.

I would be truly grateful for and help or advice!

Thanks

[nike123]

First guess:
System overcharged. High current at start-up when not enough time is passed for pressure equalization. Check your current and charge by weight.

What is compressor type/size/voltage/#phase?
What is Expansion device?

[KBSOL]

I'm only the electrician so I don't entirely understand what you say.

However I think you're suggesting the compressor overloads and cuts out internally? It is the controller which is switching the compressor.

Other than that, the compressor is single phase and about 450W at 240V.

Thanks for your time.

[nike123]

I'm only the electrician so I don't entirely understand what you say.

However I think you're suggesting the compressor overloads and cuts out internally? It is the controller which is switching the compressor.

Other than that, the compressor is single phase and about 450W at 240V.

Thanks for your time.

If you are electrician, check that every time compressor stops, its connections are free of any voltage and report here if that is the case.

[KBSOL]

When the compressor is off, there is no voltage applied. Voltage appears for a split second when temperature moves up from 4 to 5 degrees.

[nike123]

When the compressor is off, there is no voltage applied. Voltage appears for a split second when temperature moves up from 4 to 5 degrees.

Compressor and his start circuit (capacitor and start relay) could be supplied from extension cord. Check if compressor run continuously and cools if supplied with extension cord. Do not try to start it without starting circuit.
If runs, your thermostat or control PCB (relay) is faulty.
Otherwise, compressor is overcharged or starting relay/capacitor is faulty or compressor is damaged.

[KBSOL]

Right I have done this and the compressor runs continuously with no problems.

Like you say it is probably the controller.
It's difficult to analyse this part as the fridge is needed 24 hours a day.

I'd be interested to see if anyone else has had problems like this?

[stevo]

Right I have done this and the compressor runs continuously with no problems.

Like you say it is probably the controller.
It's difficult to analyse this part as the fridge is needed 24 hours a day.

I'd be interested to see if anyone else has had problems like this?

These controllers usually weld the relay contacts ! so cabinet runs continuously ! fitting an Eliwell 961 should solve the problem ! http://www.ryanairconspares.com/eliwell-id961-eliwell-controller-refrigeration-units-cycle-p-1447.html I think they do a 230v version also.

[Yuri B.]

The logics of the controller seemingly (slightly) "went mad." (however I would also tried to change the sensor, just to be 100% sure of that fact).

Introduce for safety of the compressor a time relay with some 3 min delay on the switching on of the comp's contactor - if a new controller is too expensive for you now.

[KBSOL]

These controllers usually weld the relay contacts
Hahahah, been there done that!!!

I replaced the internal relay (12A) with an alternative one at 30A. Hasn't frozen up since.

The fridge would be okay now if the controller wasn't acting mad!

Hopefully fitting a different relay has not affected the controllers logic because the coil uses too much power or something. It did work fine for 2 months with this new relay, only started when it was regassed.

Not given much thought to a time delay, good suggestion Yuri B.

[KBSOL]

Just an update.

Got it sorted now!!!

I checked the compressor differential working temperature setting on the controller and it was set at 1.

Obviously the temperature will bounce between 4 and 5 a couple of times when the temperature reading is bang on between them, so naturally it will switch off after a second as it goes back to 4!!

Anyway I dont think it was switching back on when it reached 7 degrees, just the compressor off time happened to be similar to the time taken for the fridge to warm up from 5 to 7 degrees.

Never mind!!! Thanks everyone.