Trouble understanding my refrigerator type

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Old 12-01-17, 03:15 AM
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Trouble understanding my refrigerator type

Hi Guys,

I am a noob here, so pardon me if I haven't introduced myself in a section where I was suppose to do that first. I am from Melbourne, Australia & I am having trouble with few things about my fridge.
Before, I post a separate thread about my issues with it, I thought I might start with a slightly simpler thread
to get some advice to find out whether DIY'ing this fridge is beyond my scope of not.

I have uploaded below pictures. Basically, the setup of my refrigerator's freezer & fridge is not consistent with what I have been watching so far about how the two are inter related.

As in below pictures, mine appears to have a separate evaporator for the fridge compartment than channelling the cold air from the freezer compartment using a fan(freezer it at top with a separate door.

The brand is Fisher & Paykel, and I'm not sure what the model number is, but it is around ten years or so old with two door, & the top door being the freezer one. And it's around 350 litre in capacity.

There is a small hole from the freezer compartment at the bottom of the freezer evaporator that opens to the fridge compartment. I looks like a one to direct warm air from the defrost heater in the fridge compartment to the freezer & to drain the defrosted water from the freezer into the fridge compartment and then to the bottom of the fridge(which is directed to outside from a small hole onto a tray outside the fridge at the back of it).

I can't see any defrost heaters on the freezer evaporator(see photos).

The fan on the freezer compartment blows air from behind the evaporator into the front storage area of the freezer(not the other way around). So, I have my doubts whether the freezer air get into the fridge compartment much, but I suspect it does through that small hole I described above, but not in a major way.

I have two questions if you don't mind.

1)Is this different from most of the refrigerators out there and it has two separate dedicated evaporators for the freezer & the fridge and only a minute amount of cold air travels from the freezer to the fridge?!!

2)I can't find any access to the condenser coil which appears to be going into the side of the fridge without having any access to clean it(see the pictures). Does that mean the condenser coil is inaccessible and does NOT need cleaning?!!


Thank you for any advice or tips that you can offer.
 
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Last edited by DIYfly; 12-01-17 at 06:15 AM.
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  #2  
Old 12-01-17, 03:59 AM
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This is a close-up of the above mentioned vent/drain hole between the freezer & the fridge(from fridge view).
 
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Old 12-01-17, 04:10 AM
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BTW, the fan in the freezer is working fine.
 
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Old 12-01-17, 04:42 AM
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G'day, mate. No worries, we don't have an intro section. One of the appliance pros should be along, they must be sleeping late today.
 
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Old 12-01-17, 06:33 AM
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Thanx mate.
It would be great if somebody who knows this type of refrigerators can decode the puzzle for me.
 
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Old 12-01-17, 08:13 AM
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I see nobody's chimed in yet; I'll poke the refrigeration mod's.

[Side note: Spent three weeks deployed to Perth (RAAF Pearce) in 1987; best place I ever visited in my 27 year Marine career].
 
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Old 12-01-17, 08:15 AM
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Well, here's what little bit I know. While recently shopping for a fridge (not needed after all...whew) I saw several models that made quite a selling point of having different coils for the freezer and fridge compartments. Supposedly allowed greater control over temps. Not exposed like yours is, but basically the same setup. We're only about 10 yrs behind the rest of the world in appliance design...look at front load washers and dryers and even all-in-one machines.
 
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Old 12-01-17, 08:24 AM
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I suppose it would be like having 2 zone (or whatever the proper term is) HVAC; more efficient overall to control the sections separately? Also easier to regulate the individual temps I suppose.
 
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Old 12-01-17, 10:00 AM
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That is a pretty strange design. Usually only high end fridges use dual evaporators. They also use two compressors. The piece on the back of the fridge is called a cold plate evaporator. This style is real popular with dorm and bar type fridges. Your fridge uses the outer cabinet to dissipate heat and that is the condensor.

There is also a defrost heater in the freezer evaporator and that device on the upper top left is most likely the defrost thermostat.

That hole between the fridge and freezer is to equalize/release pressure between the sides so that the doors close. Since it's at the top of the fridge... some cold air will fall thru it from the freezer.
 

Last edited by PJmax; 12-01-17 at 05:07 PM. Reason: correct mistake
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Old 12-01-17, 11:00 AM
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Thank you.
the_tow_guy, you've been here since 2001, and that means this forum is legendary indeed.
It's a pity I haven't joined this forum many many years ago
I would've learnt a lot and contributed a lot as well.

Its' great you have some down under experiences in your resume.
There are so many other great places to visit in Australia. Drop in again to see the
vast landscape with many places to visit and enjoy.
 
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Old 12-01-17, 11:05 AM
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Hi GunGuy45,

I think this Fisher & Paykel refrigerator is an earlier version of dual evaporator ones.
Even though there is a fan in the freezer evaporator to blow the cold air onto the frozen food in it,
there is no fan for the fridge evaporator.
 
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Old 12-01-17, 11:37 AM
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Hi Pjmax,
I think there are single compressor dual evaporator refrigerators, particularly the ones made in Korea like GE, LG, etc.
This Fisher & Paykel is a New zealand company, but I wouldn't have a clue whether it is was made in New zealand, Australia or Asia.

When you said "The piece on the back of the fridge is called a cold plate condensor",
Did you mean the piece I thought and described as the fridge compartment evaporator or the piece that I described as the defrost heater(the one just under the 'fridge evaporator')?!

Please refer to the below picture, so you know what I meant.

The reason I thought it is the fridge compartment evaporator is because I have seen ice build up on it from time to time, and it's generally cold(but there is an issue now).

I can't locate any defrost heater in the freezer evaporator, so that's why I thought the freezer evaporator relies on the heater in the fridge compartment for defrosting & I thought it's done by drawing the hot air out of the fridge compartment during the defrost heat cycle(triggered by a mechanical sort of timer that I pictured below next to the compressor) & generally drawing slightly comparatively warmer air out of the fridge compartment as well(through the hole between the fridge & freezer)

Please tell me If I am wrong.

I also think the device on the top left of the freezer evaporator is the defrost thermostat for the freezer, but I am thinking there is no dedicated heater to defrost the freezer evaporator(I hope I am wrong about that). The "defrost thermostat" on the freezer evaporator top left corner has both mains electricity live and neutral wires going into it, and then the yellow wire that seems to be doing something, so may be there is a defrost heater hiding behind the evaporator, even though I couldn't see a one?! May be that thermostat switch is a defrost heater as well?
 
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Old 12-01-17, 05:16 PM
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My apologies..... cold plate evaporator. I corrected my post.

The yellow line traces the defrost heating element. It is intertwined inside the evaporator coil and that device on the upper left should be inline with one of the heater wires. That is the thermostat that keeps the defrost heater from melting the plastic insides of the freezer. Those thermostats go bad constantly. Hard to check. The thermostat opens above roughly 40f to turn the heating element off. During the defrost cycle.... that thermostat should cycle on and off. The thermostat needs to be checked for continuity. It should be shorted at freezing.

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Old 12-01-17, 05:33 PM
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Hi Pjmax,
Thank you for clarifying that.
I think I have just enough understanding now to share my problem.
I'm wondering whether I should start a new thread or continue posting the issue with more pictures on this thread?!
Basically, the freezer is working 'fine'. By that I meant the freezer freezes up things fairly quickly and doesn't look like it's developing frost. The fridge on the other hand doesn't get cold enough or doesn't get cold at all. I noticed frost/ice
on the fridge evaporator from time to time, but didn't think it as a problem as the defrost heater takes care of it.(was taking care of when it appeared to be working).
After cleaning and leaving the refrigerator turned off over a day, the problem still hasn't fixed itself.
I have made few diagrams about the way it is wired with the fridge thermostat etc.
Basically, freezer is the only thing that is working atm. The compressor runs non stop.
Defrost timers is a sort of electrical/mechanical type(right next to the compressor), which turned manually to see
whether the defrost heater comes on in the fridge, but it doesn't. Heater shows about 5k ohm resistance when checked open circuit. I even ran it with the fridge defrost heater disconnected but to no good.
 
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Last edited by DIYfly; 12-01-17 at 05:52 PM.
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Old 12-01-17, 05:39 PM
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That cold plate type of cooling is not very rapid. It takes a long time to generate cold. If you are getting ice on it continuously... then it sounds like the door gasket is leaking or the door is spending too much time open.

This is actually the first time I've seen a cold plate used in a large fridge. I don't think I've ever seen a defrost heater on one either. Usually when there is an actual evaporator coil in the freezer..... moving air takes care of the fridge.

So far..... I haven't seen a way for you to control the fridge or freezer separately. With only one compressor.... it would be pretty difficult.


I don't know what other pics you could post that would be helpful.... but continue here. Don't start a new thread.
 
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Old 12-01-17, 05:58 PM
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Thanx Pjmax.
Please have a look at the diagram and the extra pictures I added to the previous post.

I also had bizarre voltage reading as indicated in the below picture, but I couldn't reproduce those voltage reading after cleaning the freezer and fridge properly & leaving it open for over a day. So, now I see 240V between the defrost heater in the fridge compartment, but I am yet to see or feel it hot. I guess the when the thermostat is closed circuit, the defrost heater doesn't come on 'cos the defrost heater on the fridge is activated by the defrost timer, but only if the thermostat is open circuit, so I think that makes sense. Defrost timers shuts off the compressor during defrost cycle.
 
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Old 12-01-17, 06:05 PM
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Since the open resistance of the fridge defrost heater is 5K..... it makes sense that the heater is across the thermostat and is active every time the thermostat shuts off. It wouldn't get too hot.
 
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Old 12-01-17, 06:05 PM
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Fridge is NOT cooling regardless of how cold the setting on the thermostat & how long I leave it running, so definitely not working. Freezer on the other hand kicks in within an hour. I even tried with fridge compartment defrost heater disconnected to see if that was causing problems by staying hot or something along those lines, but that didn't produce any good results either.
 
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Old 12-01-17, 06:10 PM
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Ok.... so the fridge is not cooling.... at all. That unit has technically two evaporator coils on one compressor. I'm guessing there are two real small lines..... one to each coil. Those are called capillary tubes. They control the amount of liquid refrigerant allowed into the coil. If the freezer one is working but the fridge one is not..... I would suspect a plugged cap tube for the fridge.

I don't think being low on refrigerant would affect just one coil but it is possible.
 
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Old 12-01-17, 06:12 PM
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Yeah, I found it kinda bizarre the fridge defrost heater is wired across the in/out pins of the fridge thermostat, but it must have had been working. I have actually tested the fridge defrost heater by setting the defrost timer into defrost spot & opening one of the wires that goes to the thermostat(the orange one), and waited to see if the heater gets hot, but couldn't feel anything after trying few minutes or so.
 
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Last edited by DIYfly; 12-01-17 at 06:38 PM.
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Old 12-01-17, 06:19 PM
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Yes, the thought of being low on refrigerant also crossed my mind then like you I thought it should've affected the freezer as well, at least to a certain degree. Since the freezer is still appearing to be thriving, I wasn't sure whether it was an electrical issue or a refrigerant plumbing issue. I wanted to rule out all the electrical fault possibilities first by understanding how it is wired first. I don't think I still understand how the defrost timer is wired up with the heater coils, particularly the role of that orange wire that goes to the fridge thermostat & the fridge defrost heater, but I am beginning get some degree of understanding.
I've been wondering whether there is a proportion valve that controls how cold the fridge evaporator gets or may be it's solely done by the fridge thermostat(which appear to be controlling the coldness for freezer as well), combined with plumbing restrictions built into the fridge evaporator. Overall, fridge evaporator has less length of plumbing and made of painted metal sheet, so I guess that reduces the heat transfer.

And yeah, I'm thinking the plumbing to the fridge evaporator might have had plugged up over time for some reason, assuming I have ruled out all the electrical faults.
 

Last edited by DIYfly; 12-01-17 at 07:05 PM.
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Old 12-01-17, 06:25 PM
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I guess, repairing a plugged up fridge evaporator tube is beyond my 'expertise', so I might be looking at either discarding the fridge or modifying it to work like an old skool fridge where the fridge compartment get all of coldness from the freezer.
 
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Old 12-02-17, 08:48 PM
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I understand a bit more about this refrigerator now & I think I know just enough to make a DIY modification project out of it.
Basically, the freezer is controlled by the thermostat in the fridge compartment that explains why the freezer has been running non stop while the fridge isn't getting colder(due to a faulty/plugged fridge evaporator).
Freezer evaporator has it's own thermostat/thermal switch triggered defrost heater which either works independently of the defrost cycle triggered by the defrost timer or most likely triggered by the defrost timer, but still switched on or off by the thermal switch on the freezer evaporator.

Since it appears the fridge evaporator has gone kaput & my chances of fixing it economically may be futile, I might be able to drlll a hole from the fridge compartment to the fridge and enlarge the existing small drain hole at the back of the freezer compartment to allow the air circulation & get the cold air into the fridge, while it's still controlled by the thermostat(the main & only thermostat that controls the compressor). I might have to disconnect the defrost heater attached to the freezer evaporator though I am not sure at this stage. I have to see how it goes.
I think my idea will work ok. I can basically attach a small duct from the freezer fan to the floor of the freezer where I am planning to drill the hole.

Any thoughts guys?

Thank you PJmax for your advice and tips.
I found the defrost heater behind the evaporator & tested the thermal switch that activates the power to it and it works fine.

Only faulty component appears to be the plugged up fridge evaporator as you pointed out before. I have also been wondering whether there is a proportioning valve in the condenser side of the plumbing, but even if there is, I doubt it is economically viable for me to attempt to replace or repair it as it would dictate that I need to recharge the refrigerator after that, and that is apparently not possible to get done cheaply here in Australia at the moment as we can't purchase R134a off the shelf.

Overall I don't think it is an efficient dual evaporator system because there was no independent thermostats for fridge and freezer and there is no fan on the fridge side. But, it has been serving me since 2008 & cost me $350 as a used one, so I think it has been a good enough one.

And I think I might have figured a way to get more life out of it as a fridge only.
refrigerator

Overall, I am not too sure whether it has been a power saving good refrigerator.
I am not too comfortable about the condenser coil being hidden inside the side panel because I am not sure it is getting cooled down sufficiently(there is no fan and it's inside a confined area). But, it's possible I might be wrong about that.
 

Last edited by DIYfly; 12-02-17 at 10:31 PM.
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Old 12-02-17, 09:32 PM
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I think it would run more efficiently with an exposed condensor coil. It seems to me to be counterproductive to heat the case of a refrigerator.

I would definitely experiment with moving cold air in from the freezer.
 
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Old 12-02-17, 10:39 PM
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Thanx Pete.
ATM, I'm leaving it alone for a week and will get into the project over next weekend.
I think the plugged up fridge evaporator might mean more refrigerant gets into the freezer evaporator and make it
produce the freeze even more quickly, but that would depend how the two lines from the condenser are created, be it a natural restriction for the fridge evaporator to ensure it makes less cold or whether there is a proportioning valve.
I think it is the former, because that might explain the blockage in the fridge evaporator capillaries.(Fridge evaporator capillary pipe may be even thinner with more restrictions to reduce the freeze efficiency and probably more prone to getting blocked by unwanted chemicals in the refrigerant or in the lubrication oil. Of course, I'm speculating here.
 
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Old 12-02-17, 11:20 PM
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And yes I agree with you. It can't be a good thing to enclose and seal the condenser on the side of the refrigerator.
It must be trapping some of the heat inside the case and transfer some of that heat into the interior.
I always preferred external condensers where we can wipe it clean when dirty.

The chest freezer that I temporarily turned into the fridge (until I get this refrigerator fixed) has an old style grill
condenser at the back of the chest freezer. I like it that way, so I can clean it when it's dusty. It is just once every few months of spending under 2 minutes to vacuum the dust off.
I think they started enclosing or hiding the condenser for cosmetic reasons and safety reasons, but like you, I believe it does not help with thermal efficiency.

Cheers
 
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Old 12-02-17, 11:23 PM
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I'll post the outcome of my project with photos in a new thread soon.
 
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