The compressor fridge stopped working two days ago, the going light continuously on, and the fridge defrosting. We turned it off, as i was concerned it may have lost gas. After arriving at a caravan park at Fitz Roy crossing, we turned it back on, and it appeared to be working again. Now everything is frozen again, and down to temperature. I think it went out on high discharge temperature, and just needed a night to cool down been 40 degrees over the last couple of days.
However, there s a problem with our fridge, as part of manufacture. Its a Dometic (Waeco) 216 liter, and it looks like they have just taken a compressor assy. out from a standard chest type portable fridge, and mounted it up behind our cabinet. The issue is that the portable fridges vent from the side, pulling air across the back of the chest type. So the condenser is flat against the enclosure wall with about 25mm of clearance. I notice on later models the condenser/fan assembly has been laid face down, so that the cooling air is sucked up, and out through the top vent.
I'm thinking that I have to do something to improve the airflow through the condenser, otherwise the system will go down again. One thing I can do is fit a more powerful fan, so I need details of where to buy better fans. The other thing I need to do, is because it is a recess designed for a 3 way, there is no way to gain access to the essential workings of the compressor unit, so I'm thinking of firstly fitting an access hatch. The only way now to do anything to the fridge is by removing it.
So access hatch, and a more powerful fan. How to give the condenser more cooling air, I won't be able to address that until I can get a closer look at what I have to work with.
I reckon you are on the right track with your plan. Access to all these things (fridges, stoves, micro waves , hot water units, diesel heaters ,pumps etc.) - is important , something van builders do not worry about. You are not always in a covered workshop , with tools and time on your hands when things go wrong ! The air flow around a caravan fridge condenser needs to be clear, unrestricted and preferably fan forced especially if used in above average temperature Northern conditions.
-- Edited by KJB on Thursday 3rd of September 2020 03:47:03 PM
You can get them from Mwave or Techbuy. But any fan moving some air is better than nothing. Also in a push pull arrangement if possible & baffles if needed so the air is actually being moved through the space.
There is no point having a grill & covering half of it with a fan. Better off putting 2 fans side by side on the grill so air does not circulate back through that grill.
Over the years I have bought about 60 Noctua fans. 120 & 92mm fans in this photo, dual xeon cpu. These are the non industrial fans. Quieter when 6 computers running!
You know Johnathon (checked your profile) I put this post up for you. Subject right up your alley. But I am also sure that half our power consumption (batteries) is due to the condenser preforming poorly due to lack of cooling air. If I get a chance and can get my arm down far enough, I'll post some pictures, maybe some ideas will be suggested. Will have to be our next camp spot, tomorrow perhaps. And yeah, voltage drop is another point to consider.
-- Edited by iana on Thursday 3rd of September 2020 07:41:29 PM
Because we live out of a car & usually sleep in it space is at a premium. I couldn't have any more battery capacity but could make things more efficient without taking up any more space.
What I have noticed with days of testing is that when the voltage dropped the fridge's compressor slowed down & didn't use as much current. The consequence of this is the fridge is running longer trying to catch up.
If the fridge is under stress it is going to be running longer. The simplest solution is put extra heavy gauge wire from the battery to the fridge & also upgrade the wire in the fridge from the socket to the circuit board. My 28L fridge had 55cm of wire internally, so 1.1 metres for + & - .
The fridge will run fine if not under stress, but when it's hot, voltage down a bit, poor ventilation (which could be taking air from a warm place), ordinary insulation (you could add some to door at the very least), opening the door too often (I did a test years ago via my UPS logging our home fridge's power consumption & it is frightening how much extra power the fridge needs to cool it down again after an evening of regularly opening the door), stop opening the door!
You need to fix all these individual issues so the fridge will cope better under stressful conditions.
Some of the data I collected when testing the 28L fridge.
Attached are some pictures, note the 3 holes in the shelf from below, The fan facing the enclosure wall with about 50mm clearance. The vent is below as for a 3 way fridge, and the exit vent is on the roof.
-- Edited by iana on Friday 4th of September 2020 06:06:38 PM
What is the total cross sectional area of all the holes & gaps below the fridge?
1 large hole is always better than 4 small holes.
What is the total cross sectional area of all the holes & gaps above the fridge?
Clean all the dust off the condenser, compressor & fan blades for a start.
What I would do if there are no obstacles to get the air drawing in:
Put baffles around the fan & cut a new hole between fan & wall, & close other holes. Then the fan will only be pulling in air from outside this space, instead of simply circulating the air around inside the space.
Add a fan at the top of the fridge to get the air out to assist the fan on the condenser.
50mm gap between the fan & the wall is bearable! "as I said the compressor unit is not really accessible, I can get an arm down and touch the fan etc., but can't work on it."
What is the total cross sectional area of all the holes & gaps below the fridge? "Below the compressor is a large vent/panel as installed for a 3 way fridge."
1 large hole is always better than 4 small holes. "I haven't worked out the fan direction yet, those three holes my not be doing anything."
What is the total cross sectional area of all the holes & gaps above the fridge? "Large top vent on the roof, my only access".
Clean all the dust off the condenser, compressor & fan blades for a start. "Looks crappy, but to dust it off, I need to remove the fridge out from the enclosure. Its just done s few Ks around Aus."
I'm going to call this "Option 1"
What I would do if there are no obstacles to get the air drawing in:
Put baffles around the fan & cut a new hole between fan & wall, & close other holes. Then the fan will only be pulling in air from outside this space, instead of simply circulating the air around inside the space.
Add a fan at the top of the fridge to get the air out to assist the fan on the condenser.
So for $3000 bucks, that is a pretty crap design of a fridge and installation. Don't like that unsupported liquid line either. The newer model, that I saw a picture of, had the condenser mounted horizontal on that shelf, obviously with a big hole cut in the shelf giving improved airflow, but the high pressure gas line broke as it was unsupported. I imagine the condenser mounted vertically like ours is, would be more efficient, but I may be wrong.
OK option 1 would work, however there are other ideas to consider:-
1/ Instead of ducting the air from below, where you have the words "New opening approx. 50mm x 120mm, is the side of the van. maybe a vent opening could be cut out there direct to the outside, with baffles etc., then the entire lower cavity say a meter x 600mm could be filled with insulation. The lower now redundant vent closed off with an insulated access door.
2/ Where you have the word "Baffle" there is a cavity wall of about 40mm, this has a cupboard against it on the other side, a vent could be put straight through, I know that these fridges are installed with a fan assisted vent from inside the van. This thought may not be an ideal, but worth considering.
Make a template out of thick paper or cardboard (cereal packet etc) & sticky tape so it folds up as one origami piece (overlap edges where appropriate). Once you are happy cut out of 0.5mm aluminium sheet, which you can cut with kitchen scissors or score with a knife & flex back & forth & snap. Sand edges & corners so you don't cut yourself while installing or removing later (I always smooth edges). Pre drill holes for screws & or cable ties.
The clear polycarbonate baffle was the first modification I did to the fridge. Then the foam for acoustic insulation which in the meantime I have made further modifications.
The aluminium angle sections I added to mount the larger 120mm fan. I have since tapered the angle for a bit better air flow (as per blue outline).
Take your time & think about the process, assembly, access, fastening, removal for maintenance, get off the project for a week, Einstein came up with E=mc˛ in his sleep, so a baffle show be a piece of cake!
Think out the airflow for the most efficiency & easy of assembly. Sketch up all dimensions first, elevations, plans, only then start templates.
I am now thinking that a modification of option 1 would be the go, that is removing the electric fan, Running ducting around and down to the existing vent, then mounting the fan there. It would mean no extra holes, access to the most likely part to fail, and the back space of the fridge can still be filled with insulation.
These fans do not operate as efficiently up against a grill. It would be better to mount it horizontally a little above the grill (it would also a bit out of the weather).
Also due to the long ducting I would double the cross sectional area of the fan area as the ducting walls create air friction.
I used a bit of open cell foam for a dust filter. Works well, not blocking too much air but still providing enough interruptions to air flow to block dust (behind your external grill, not next to the fan as in my 28L fridge's situation due to limited space).
The first Noctua fan I put in didn't have enough pressure, but the Noctua industrial model has enough pressure with the filter.
Iana we have the same fridge as you. Most of the suggestions here are about getting airflow over the condenser however the problem may be simpler than that. Our fridge does not like it when the battery voltage drops even slightly below 12.5volts and the red light comes on indicating low voltage. Once the motor stops the battery recovers just enough voltage to start the motor again so the fridge just keeps cycling on and off. As suggested replacing the wire between the fridge and the battery may solve the problem.
-- Edited by Gus1949 on Tuesday 8th of September 2020 02:35:48 PM
Your fridge is rated at 10.5 amps. Let's say it typically use 7 amps when running & 5 metres to the battery, so 10 metre + & - Even if you are using the recommended 12awg wire you have a voltage drop or 0.37 volts.
Voltage drop may be playing a part, but this was the first time the compressor has not been doing its job. The cable length would be a run of more like 7 meters, i.e. 14m of cable. I think the fan installation needs some serious rework, and if I have to reduce the cable run, so be it.
