3 way fridge - 12v not working - HELP!

Submitted: Monday, Feb 21, 2005 at 09:42
ThreadID: 20629 Views:2441 Replies:9 FollowUps:10
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Hello again,

While you were all in Wandin Marko was finishing off his dual battery system on the 80series. Ran extra ciggy plugs down the back and a big power cable for the fridge. Installed the 90ah GSM battery hooked everything up excellent.

Plugged in the fridge the night before on 240v worked a treat. My plan was to plug it into the 12v all day to see how long the battery would last me. All day and the temp just kept rising. The fridge was 'supposedly' working. Heat coming out of the exhaust flue. My two new 12v fans working, but no cooling to be had. Oh fridge is RC1180.

So with Flinders Trip just 9 sleeps away I would love to have the fridge running on 12v!!! (at night i'll run it on gas but would expect it to cool whilst driving and maybe stopping for lunch etc)

If suggestions are take it to a fridge man - any suggetions around Melbourne?

Thanks in advance!
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Reply By: AT4WD ADVENTURES - Monday, Feb 21, 2005 at 10:43

Monday, Feb 21, 2005 at 10:43
Hey Marko,

I am not familar with these units but have a basic understanding of how a 3 way works. So here is my two bobs worth.

I would assume that on 240volt and gas the thermostat works and on 12volt it doesn't. Make sure that the selection of 12volt via the appropriate switch is indeed in the right position. Remember that on 12volt the fridge will probably be not that efficent. Remember that these fridges use a heat source to boil a liquid and a 12volt element running off a battery with out charge is not going to last long at all.
You may well find that the element was warm but not hot enough to bring the liquid to the boil therefore not turning to gas and rising through the fridge tubes and not going through the whole heat exchange process but rather giving the appearance of doing so.

Regards

Stuart M
AnswerID: 99290

Reply By: AdrianLR - Monday, Feb 21, 2005 at 10:45

Monday, Feb 21, 2005 at 10:45
Try it without the fans in case they are disrupting the airflow sufficiently that the ammonia is not recondensing in the right part of the system. They should be set up to suck air from the top so that the original path is followed as closely as possible.

Another test may be to run it on 240 but with the fans going (may need re-wiring to do this?)

Adrian
AnswerID: 99291

Follow Up By: Marko - Monday, Feb 21, 2005 at 10:59

Monday, Feb 21, 2005 at 10:59
Hi Adrian,

That seems to make sense. They are currently suck air from the top and blowing it down over the coils. (i know this is not recommended but i had my reasons for doing it that way) So turning the fans upside down is what you are suggesting? Drawing air from the bottom of the fridge up through the coils and then out?

Yes it makes more sense cause as you guessed the fans aren't working on 240v. I shall try it this evening and see what happens. Thank you!

marko
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FollowupID: 357607

Follow Up By: AdrianLR - Monday, Feb 21, 2005 at 11:22

Monday, Feb 21, 2005 at 11:22
Marko,

That's right - turn the fans upside down.

I assume that the fridge was really level when you ran it. Because the system is more marginal on 12v this is even more important. Also check that you are getting at least 12v at the fridge. Check the ground connection (if you've used the body rather than a separate wire to the battery as the body is not always reliable). Check the voltage with the motor running and switched off as the fridge will put a very high load on the battery. As a previous poster said, it may feel warm but it needs to be very hot.

Check out www.rvmobile.com particularly the technical section. This is a great site dedicated to mobile refrigeration and gives a very clear explanation of the theory of 3-ways.

Adrian
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Follow Up By: Nudenut - Monday, Feb 21, 2005 at 12:20

Monday, Feb 21, 2005 at 12:20
Hot air rises...and that is the way the condenser is designed to operate.....

to make it more efficient the fans must be installed to have the airflow in the same direction.

Does the unit operate on 240v or gas?..if so, it aint in the refrigeration side.....and your problem must be related to 12v side?

Heat from the flue generally says its working ...but how much? the more heat you have the harder they work...(within reason) so if 12v heater element is getting hot but not getting full 12v then this may be problem as it may not be getting to full operating temp....Is the unit second hand? did previous owner have 12v heater problems and put in wrong size heater?...

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Follow Up By: Marko - Monday, Feb 21, 2005 at 13:04

Monday, Feb 21, 2005 at 13:04
Gday Nudenut (hmmmm)

It runs fine on 240v and gas but neither of those power sources have the fans working.

From memory the flue was very hot on 240v but just warm on 12v.

I have owned it since new. I reckon it's my fan setup that's causing the problems. I've run really thick cable, wired it in beautifully. The only thing i did wrong (and i knew it) was put the fans facing the wrong way.
Didn't think it would make much difference, just improve airflow and stuff.

I think switching them over will do the trick. Anyway I'll try that tonight and hopefully by morning I will have my answer.

Thank you

Marko
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Follow Up By: Nudenut - Monday, Feb 21, 2005 at 13:34

Monday, Feb 21, 2005 at 13:34
if the flue is only getting warm its probably not hot enough....

the fans arent cooling the generator (heat box where 12v element is) down?

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Reply By: Member - Banjo (SA) - Monday, Feb 21, 2005 at 13:14

Monday, Feb 21, 2005 at 13:14
If the thing runs well on 240 and gas, it runs ! If the flue is hot on 12 volt, the element is good. This should mean you simply have to have the fridge level, and get the gas circulating - see prior posts on tipping the thing sideways to stir up the gas flow. Mine has been running well on 12 volts while mobile- I have a small 12 volt 'puter fan at the rear for circulation - guess you should ensure that you only have minor flow at the back - no wind tunnels !
AnswerID: 99310

Follow Up By: Marko - Monday, Feb 21, 2005 at 13:27

Monday, Feb 21, 2005 at 13:27
Hi Banjo,

Level......... I could have hosted the 2005 World Snooker Championships! I have tipped the thing and there was immediate gugurling. It's been running great for years until I started fiddling with it (that'll learn me).

I added two 'puter fans but they may be a bit too big. I think I will turn them around tonight to start with and run just one fan. If that works I'll get the second one working and see if it makes a difference.

Cheers!
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Reply By: Member - David 0- Monday, Feb 21, 2005 at 13:24

Monday, Feb 21, 2005 at 13:24
What was the battery voltage when u finished, If it is a 3way, it won't run for very long at all. Probably 10 minutes. Could this be why it didn't work?

Mine is on 12v only while engine running, works fine if it is already cold and full of cold stuff.
AnswerID: 99311

Follow Up By: Marko - Monday, Feb 21, 2005 at 13:32

Monday, Feb 21, 2005 at 13:32
G'day David 0,

10 minutes!!! I would have expected a few hours. Anyway I plugged it in for 2 hrs and was getting 10volts to it. I then went for a drive for an hour and it was getting 13.5 volts to it. Made no difference.

I'm going to swap the fans first and see if that does it. As I said earlier I (think) have done everything according to instructions and plans but the one thing I did wrong was put the fans in upsidedown.

I have a feeling this may fix the problem. Basically I'll try that tonight and make a report in the morning. I may even bring it in to work so I can fiddle with it during the day if I must.

Thank you all for your responses, it has been most useful!!!!!

Marko
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Reply By: AT4WD ADVENTURES - Monday, Feb 21, 2005 at 14:43

Monday, Feb 21, 2005 at 14:43
Marko,

I could almost guarentee that if your fans are blowing air backwards across the normal airpath that the fridge creates via normal convection then the fridge is not going to cool very efficently or not at all.

Swap the fans around so they drag cool air across the coils in the right direction or take them out.

As i said in my previou posts it is also dependant on the amps drawn by the 12 volt element as to how long your battery will last when not be charged whilst driving. This is why most people fit a safety relay on the 12 volt ciruit connected to the iginition switch to ensure that don't forget to isolate the 12volt element when they stop there car and come back to a dead battery an 1hr later.

Regards,

Stuart.
AnswerID: 99324

Follow Up By: Member - David 0- Tuesday, Feb 22, 2005 at 11:05

Tuesday, Feb 22, 2005 at 11:05
Yes mine has the fans blowing out the top and works fine.
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Reply By: DeanoNSW - Monday, Feb 21, 2005 at 20:40

Monday, Feb 21, 2005 at 20:40
Not sure how similar these units are to the Chescold Fridge, but if they are, on 12 volt they will do little more than hold the temp for a few hours.

I have an older Chescold, and we had to run ice blocks in the bottom of the fridge and each night they would freeze on gas. I also ended up shorting out the thermostat so that I had the fridge running flat out all the time.

On 12volt the fridge would do little more than kill the battery and barely hold the temp. From memory it would pull constant 8 amps. (not sure the specs on your fridge. ) It was (and still is) an excellent fridge for sitting in the one place running on gas. I moved to a compressor type fridge because I was sick of pulling the fridge out of the car each day, lighting the pilot and getting it going. I also got sick of having to store all our food in tuperware containers to stop it from getting wet each day as the ice would melt (only on 12 volt).

Sorry if this is bad news. I hope your fridge is a whole lot better than my old one !
AnswerID: 99372

Follow Up By: Member - David 0- Tuesday, Feb 22, 2005 at 11:08

Tuesday, Feb 22, 2005 at 11:08
Mine pulls 10.5 amps and will flatten the battery in no time. I did use it on 12 V all the way around SA for 5 weeks. I used it as a freezer. I stored all prefozen stuff in it and put a several prefrozen plastic bottles of milk in it. I used an esky for fridge and took prefrozen bottles out of freezer as required. Occassionally need to suplement with block ice. My freezer was on 12 V while engine running and on gas the rest of the time. it never got above -10degC.
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Reply By: muzzimbidgie - Monday, Feb 21, 2005 at 20:56

Monday, Feb 21, 2005 at 20:56
One last thing, not mentioned yet, I don't think.

When you switch from 240 or gas to 12v, make sure you reset the thermostat. That is, turn it to OFF and then turn it up to where it was before.

I have been doing this for a while now and it does make a small amount of difference.

Also, on my 3way in the camper, it stopped working on 12v, it turned out to be the switch itself was was not selecting 12v properley (the 3way switch), and I had to have a seperate switch wired in, which is positioned next to the fridge.

As mentioned above, I'll put money on it being the fans.
AnswerID: 99376

Reply By: pixiemops - Monday, Feb 21, 2005 at 21:47

Monday, Feb 21, 2005 at 21:47
I got the car re-wired with an 8mm cable to the back and connected with a caravan 2 pin plug. This plus the addition of 2 fans 1 blowing air up across the absorber coils and another through the condenser coils makes this finch fridge run fantastic on every source and just as good on 12v as 240v. If you do this the argument that these fridges don' t perform on 12v goes out the back window .......sorry I can't solve your problem Marko . Once sorted it will run great on 12v.
AnswerID: 99385

Reply By: Marko - Tuesday, Feb 22, 2005 at 07:46

Tuesday, Feb 22, 2005 at 07:46
Greetings,

Well went home last night and turned the fans upside down. The deep cycle battery which I run it off had full charge so I plugged her in. It had been sitting in the car all day so internally it was 30deg. Within 2hrs the fridge had dropped 10deg. The deep cycle battery still had grunt left in it.

So my problem has been solved!!! A heartfelt thankyou goes out to all within this thread. All I really wanted it to do was hold it's temp, but now it is actually dropping the temp!

I'll do some further tests over the next few days just to see what performance I'll get from it whilst away but I know that I can now leave it in the car for at least 2 hours and it will continue to keep my Boags cold!!! (and isn't that what really matters)

Cheers,

Marko
AnswerID: 99442

Follow Up By: Squizzy - Tuesday, Feb 22, 2005 at 14:04

Tuesday, Feb 22, 2005 at 14:04
Marko,

You should get 2 hours from the battery, I used to get around that when I had a 3 way.
But remember, the battery will be low and will take a while to get back to full voltage, especially if it's a deep cycle.

And what a choice of beer, BOAGS, just love it.
I used to drink it while I worked in Tassie for a while in '99.

Geoff.
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FollowupID: 357805

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