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Help! - Narcissistic Compressor Driven Fridge Thinks it's the Boss!


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The Engine driven compressor/plate/brine freezer on our 1020 is hell bent on sending me to the looney bin, and possibly divorce court.

Its a standard factory fitted interior with a top loading stainless lined freezer in chart table surrounded on all 4 sides by the brine tank and front opening fridge utilizing the back of 1 freezer wall.

Load boat up for Bay of Islands trip, go down and fire it up, Load freezer, flick compressor on and within 5 mins there's a healthy frozen line moving it's way up the walls of the freezer. Running it for 1 hour has the whole thing chilled down super well and off you go enjoying cold beers from the fridge safe in the knowledge your steaks will still be frozen days later.

Day 2, fire boat up to motor out of Tut's and head up the coast. Flick the compressor on for a cool down 'top up'. turn off after an hour and notice that it hasn't really appeared to Ice up like the day before. Doesn't concern you, maybe some kind of thermostat thing where system is telling you "hey don't worry - still all frozen in here"

Day 3, motor out of Paradise Bay towards Russel with fridge on. Hmmmm - this thing ain't working. Compressor clutch clicks in, engine revs drop a bit but nothing flowing through sight glass and return line not freezing up. Start to panic, food at the top has defrosted. Phone and ask wife to bring the 12v Dometic unit up from home when she meets you. Make plans to empty freezer and divide perishables between friends boats freezers. Revise meal plan to eat top layer of food first.

That afternoon, after picking family up from wharf you try it again and boom! - Elvis is back in the building. Freezing faster than Kim dot Coms assets. Must have been a glitch in the matrix. Yeehah, cancel plans to shorten family holiday and move on with your life.... except.... Day 4, Elvis is Dead on the Toilet. Resume panic stage... then repeat above steps for remaining 10 days of your trip.

That was our new years trip. Since then we have done a couple of overnight trips with pretty much the same result. Fantastic for a day trip, but no good for multiple days. This Labour weekend was the same - Froze down Friday, didn't work Saturday or Sunday, fired back into life Monday on the way home. 

Anyone with experience of this phenom?

Boats been back in the water for a year following a decent refit. Had never used it before then, the only modification to fridge system I undertook was remaking engine mount/compressor bracket  to relocate compressor to the space under quarter berth instead of hanging through wall of engine compartment and burning a hole in the bedding. Hoses were never disconnected in this process but the compressor orientation was altered perhaps 90 degrees - are they fussy about that?

It's been suggested it could be a jammed TXV, could this be the case or is it simply adjusted to only work above a temperature that's not low enough for the freezers purpose?

Frustrating that when it works it's amazing - but only works when it wants to.

Fire away!

 

 

 

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Will be a sticky txv valve, went through this on Kick, spent way to much money on the system so ditched it all for 12V havnt had a problem since.

Possibly wind the valve in and out a few times to free it up?

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I have made fridge service guys rich but I did learn a few things, these engine driven systems are very simple and reliable when sorted but the problem is that now most of them are what, 40 years old? So engine mounts don't work so well and make copper lines crack, flexible hoses start leaking, valves get sticky, solenoids short and compressors need servicing but If you do a full rebuild then they should go for another 40.

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A couple of things could cause this. Are you sure the sight glass was empty? Not just full of liquid? A stuck txv valve could be it, so could ice.

Does the centre of the sight glass indicate its wet? It changes Color to do that, but the actual Color depends on the unit. It’s normally indicated what Color is what on the outer ring of the sight glass. If it’s wet, change the filter/drier.

When it’s on, make certain the clutch engages, and the centre of the compressor is actually turning.

What you should see in the sight glass is 1stly nothing, then after a few seconds some liquid and bubbles. Liquid level should completely fill the sight glass, and bubbles should disappear after a few mins (not more than 10), leaving the sight glass full of clear liquid. Can look empty at this point, or maybe has a trapped bubble in it. That’s ok. Check again when fully cold but still running - full of liquid with no bubbles indicates a full gas charge. Bubbles passing thru at any stage after the first few mins indicates low gas.

Some installs are controlled with pressure regulation, but that will switch the compressor off and on as required, so you don’t have to remember.

The refrigerant gases have got really pricey over the last few years, with a bottle of r134a now being over $2k. Servicing engine driven units can be very time consuming and therefore expensive, esp if there is a really slow leak (can be virtually impossible to find!) or you need to change to a current refrigerant.

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Hi Matt

Yes the compressor works as should, and the sight glass behaves as described (fills up.and bubbles clear). It has R154 in it, the Engine is only 700hrs old and it would appear Compressor is same vintage. Once I realized we had an issue I could tell within a minute of firing the thing up if Mr Cool was in the house by touching the outlet pipe from Fridge back to compressor. It would very quickly get icy (but not at compressor end so not concerned about slugging).

It would appear that something is randomly deciding whether or not it's going to let things happen, a stuck TXV sounds like a lovely culprit... I took the panel off and found valve, buried in the insulation. I'm picking the spring above doesn't actually need to 'spring' as it looks pretty glued in place!

 

20221024_115507.jpg

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If it's a sticking TX valve, sometimes a sharp tap with a hammer will move it if it's stuck (or dirty). This is not 100%, and if it starts working only shows it is the valve, it's not fixed and would almost certainly do it again. To change the valve the unit needs the gas removed (or stored in the accumulator if fitted) unfortunately, so it's a job for a fridge tech.

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That's the capillary tube, not a spring or thermostat. 

One end has a sensing bulb that will be attached to your suction refrigerant line. The other end goes to a diaphragm at the top of the expansion valve.

It holds refrigerant in a closed system (not part of the refrigerant that passes through the condenser).

Its purpose is to open and close the txv depending on if the superheat needs to be increased or decreased.  Its length, internal diameter and bulb size is specific to the rest of the installation hence it is just coiled up. 

IMO It sounds like you need to get a professional in.  It's a $50k fine in NZ to intentionally release SGGs into the atmosphere.  And you're going to need special expensive equipment to replace the txv anyway and regas the system. 

Like you have started to do. I would expose all the working parts and connections to reduce the labour costs. 

PS: I doubt very much that you have R154 in the system... 

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1 hour ago, funlovincriminal said:

It has R154

Did you mean R152a? That's a replacement for R134a, but Ive never heard of R154 (not that that means much!) If it's right, is it new?

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Oceanair seem to be very good at dealing with engine driven compressor systems. I'd recommend them.

A sorted engine driven compressor freezer/fridge is awesome! I haven't come across anything that cools drinks faster... just got to be careful not to freeze them!

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and if you need a compresssor or parts for one like the clutch good chance it is the same as used in all the forestry equipment,  can be sourced for a quarter of the marine price.  Forestaire are a good company in Rotorua,  the receptionist there know more than most about the danfoss catalogue and replacement bits and generally had them on the shelf.

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8 hours ago, CarpeDiem said:

IMO It sounds like you need to get a professional in.  It's a $50k fine in NZ to intentionally release SGGs into the atmosphere.  And you're going to need special expensive equipment to replace the txv anyway and regas the system.

Don't fret - I'm not about to start undoing any pipes or anything - not a refrigeration technician by a long shot but also not an idiot!

Just wanting to learn as much as possible about what is in the boat and hopefully make a more accurate diagnosis of what is causing the issue.

If tapping or adjusting the txv (in and out but finishing back at same point as it started at) and checking location of bulb plus maybe exercising it a bit (plunging it alternately between cups of ice and hot water) doesn't cure it I'll get it replaced and regassed.

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