Fridge/Freezer Compressor

Today I was given the compressor as shown below , As can be seen the power and earth wiring is in place as is the capacitor, however it will not run .

i have done a basic test and there is continuity in the wires and no shorting .

i am aware that it would normally have thermostat, door switch , lighting on its circuit , and these are not attached, so ! , is there a way of fooling it to think it’s got all its bits , in an effort to get it running ?

Any advice or suggestions will be appreciated ( provided it concerns the topic in question )

Are all refrigerant lines and heat exchangers intact , and is refrigerant present and at correct "compressor off" pressure? Many modern refrigeration compressors will not run if the refrigerant is not present at the correct pressure. (at least on ones in North America that I have had dealings with)

You need to connect a switch (or link) between Live and the C terminal (un-connected in your diagram)

Manual is here https://manualzz.com/doc/53379116/danfoss-nly15kk.3-high-energy-optimized-compressor-r600a-...

Note that these units need oil for lubrication. SAE 32 "hydraulic" oil as used in many lathes should be OK.

They are also not suited to frequent stop / start cycles. They can produce significant pressures once running but won't start up against a high pressure head.

Robert G8RPI.

Umm, don't hold me to it, but I think the tag above the live screw terminal should be connected to C.

Normally the compressor is switched by a thermostat which is missing. I believe the thermostat is a simple on/off switch so a wire between C and L should turn the motor on.

Apologies in advance for any magic smoke!!!

Dave

Edited By SillyOldDuffer on 08/09/2022 17:01:35

Hi D.A.G

What are you going to do with this compressor? Fit it to a fridge or freezer?

If not, bear in mind, they're designed for compressing refrigerant gas, and has already been said, will need some lubrication.

Do they create much suction? Just musing on whether one would be suitable for de-aerating epoxy resin in a suitably sealed container.

A small reservoir on the output side could be arranged to let some lubricant drain back into the workings, possibly?

Rob

Have a root around Youtube.
A number of folk I've come across have used one for a vacuum chamber to stabilise wood for knife scales.
I've got the pressure cooker , but awaiting a suitable fridge compressor.
I can't remember where now, but I do recall reading about someone who used two in series to get a higher vacuum. (or should that be lower??)

Immerse the wood in Cactus Juice, evacuate the chamber overnight, and allow the air back in slowly; this impregnates the wood and stabilises it.
https://houseofresin.co.uk/cactus-juice-stabilizing-resin-1-89-litres-1-2-us-gallon-revised-formula/

Bill

In the past I’ve seen several write ups on the net for using these as an Airbrush Compressor with a suitable air reservoir. No mention of lubricant that I can remember other than making sure any of the original lubricant hasn’t leaked out.

Thank you all for your interest and response .

I intend to use it as a silent compressor in my workshop, I have on at the moment and find it so useful that I wanted to add an additional unit to the supply end .

It will go through a pressure switch , overcoming the start pressure issue ( thanks Costas for that )

Currently , the refrigerant is in the unit , I shall drain it and replace as suggested with a lubricant as in my present set up .

SOD : there was a black wire connected to terminal “C” , will have a go with your suggestion , unless there are other definitive directions given .

Edited By D.A.Godley on 08/09/2022 18:38:04

I hope the refrigerant isn't a CFC. If it is, releasing it to the atmosphere is a tad irresponsible, it damages the ozone layer

Unless it is still a sealed system the refrigerant will not be in it. Any liquid left wil be lubricant.
If it is still sealed it is an offence to release it. You should get a "R Gas" qualified person to recover it.
Some of the "Bambi" compressors use fridge compressors it may be worth looking at their manuals for hints.

Robert G8RPI.

Thanks Bill, that's the sort of thing I was thinking about. The pressure cooker is a good idea too.

Rob

Your pictures do not show clearly if the wires are connected to a starter. There were several types, some did not take kindly to stopping and restarting regularly or at short intervals. Noel

The start relay would be the cream (off white) coloured device.

Edited By V8Eng on 08/09/2022 20:31:45

Ignore my earlier post on "R-gas" I just noticed that it is labeled R600a That is isobutane and is NOT a CFC or regulated.

It is highly flammable though so be careful where you release it.

Robert G8RPI.

Robert : Thanks for clearing that issue up , I would say that the system is sealed and there are no leaks , thus no risk , but I will be mindful when introducing the new lubricant.

What I really need is , as requested initially , how can I wire it up so that it will run ( without the thermostat, door and light switches etc ) . So far only SOD has proffered a suggestion, but he was by no means sure , hence my desire to receive more specific or detailed ideas.

Have a read of Robert's first reply to you, post 3 in this thread.
He's given you a link to the manual, P2 of which contains a wiring diagram.

Bill

Bill : Thank you for your contribution.

It had not escaped my attention that Robert had included the link which gave valuable detail of the wiring set up for the unit in its original state , however , all that I know of electrics is that it bites if you don’t get the right bits joined up and whilst ok with engineering drawing , electrical schematics are a whole different world ! .

i have taken a look on YouTube , which may have thrown some light on how to proceed so , today , I hope to give that guidance a try , but it does mean modifying the wiring connections , so slowly slowly , and I shall see where that gets me .

David .

See my earlier post.

Connect your pressure switch between terminal C (bottom middle) and live (spare tag above brown wire is good place). That is all you need.

For testing just put a manual switch between C and live.

The start timer and overload cutout are under the white(ish) plastic moulding.

I first used a fridge compressor as an air compressor about 45 years ago.
As I mentioned before they have trouble starting against a head of pressure. You will probably need a non-return valve between the compressor and air receiver and either a depressurisation valve or small leak between compressor and NRV. Some of the Bambis use a NRV and a small normally open solenoid valve with the coil in parallel with the compressor to depressurise. A possibility to avoid the NRV is a 3 port valve with common to compressor, power off open port to vent and power on open to air receiver. However not all designs of 3 port valve will hold back pressure on the closed port.

Have used them for degassing epoxies - works very well indeed - also used as a vacuum source for a small (300x300mm) vac table to hold down printed circuit board material on a cnc router/drill. To preserve the lube I have the outlet exit the compressor vertically into the bottom of a brass funnel filled with open neoprene sponge - the sponge traps all oil and the oil drains back into the compressor when it is not running - seems to work ok - this specific one has about 1500 hours on it as a vac pump, and have never needed to add oil.