A fridge in my service van

[fridge doctor]

Q. What's the most important tool you have to enable you to repair your customer's cooling problems?
A. Your van.... Without it you are stuffed !

Next:

Q. 2nd most important thing you need on a daily basis
A. Sandwiches, choc bars etc. + water or soft drinks and plenty of it to keep your energy and concentration levels up !!!

Q. So how do I get a decent fridge in the back of my van. I have installed a little thermo-electric job running from an aux battery, but the temp in the back of my van during the day is between 35-45C, and the unit has had little effect. I tried improving performance by slapping ice packs and pre-chilled food/drink in (contrary to manufacturer advice) - (don't know why), but it has not helped at all. Not certain of the principle involved in this technology, what can I do to improve things? My next step is to paint the roof of the (dark blue) van with a silver spray to reduce heat inside. Also on the list is a 12v fan to extract air from the space, and thirdly I will line the plastic inside of the fridge cabinet with aluminium which will provide a heat sink for whatever cooling is available. Any other ideas guy's ?

[Air duster]

To maximize the usefulness of the thermoelectric cooler make sure that the outside heat sink on the PJ "peltier junction" is cooled properly. Make sure the fan is running, and it has an ample supply of cool air. They are a bit of a power hog for their cooling size. In general, PJ’s are a pretty inefficient cooling device.

The unit may have a high temp cutoff on the outside portion of the PJ to stop it from overheating if the internal fan fails. If you van is that hot inside, it may jut be tripping out on overheat. You could get by that by putting a fresh air intake duct (drier vent hose) going to the air inlet on the cooler. That may avoid it tripping out on overheat. You could put a little fan in the duct to help the air through to the cooler.

If you wanted to go psycho you could take the cooler apart and take off the outside heatsink to the PJ and make a water block for it and circulate the water to an outside radiator.



Another option would be to buy one of those little table top fridges that they sell for $50 to $100 with a real refrigerant ,compressor system, and put a Danfoss 12V DC compressor in it. You will get a lot more cooling per amp of operating load.

Or find a 12V to 120V inverter that will drive the existing compressor properly. You could probably get by with a modified sine wave inverter, but I would suggest getting a small pure sine wave inverter. Induction motors run a lot better on a real sine wave. The sine wave inverter will cost more than the fridge.

I would go with which ever is cheaper. A 12V DC dan foss compressor to replace the compressor that is in it, or get an inverter to drive the existing compressor that is in the fridge.

Or you could just get a DC compressor and hook it up to a BIG coleman cooler. Run a few loops of copper pipe around the top of the cooler. and out a notch in the side. The condenser could be mounted under the van with a little 12V DC fan on it.

[Brian_UK]

Yep, agreed, dump the thermoelectric and get a compressor fridge.

Either make your own using the little 12v Danfoss or buy one from a caravan dealer; don't get one from a marine chandler 'cos it'll cost twice as much.

[Air duster]

A good example of pre-built ones that I know of is Engel.

http://www.engelaustralia.com.au/

A representative price list from an American distributor.

http://www.everythingsuv.com/engel-esuv.asp

More example prices can be found by doing a google product search.

http://www.google.com/products?um=1&...engel%20fridge

[chillin out]

You could use the cooling from the A/C if you had it in the van.

Or how about fitting a A/C compressor driven off the engine and then connect it to a fridge in the back.

Chillin

[fridge doctor]

Thanks for your replies, I do like the "proper fridge idea", but then naturally I would ! Probably involve a lot of extra cost out here though, and would have to adapt it by extending the condenser under the van as Air Duster said. Bits like 12V Danfoss may be a problem too.
I have got AC on the van (Chillin out) but it wouldn't help me to get cooling if I'm working on an installation (often) or multi AC maintenance in one location for long period, so can't do that - but thanks.
I suppose absorption may be an answer, but they are a bit bulky, and ideally I wanted to be able to make the unit reasonably portable. Will have a look at those web sites (Thanks Air Duster), see if anything there helps.

[Air duster]

Thanks for your replies, I do like the "proper fridge idea", but then naturally I would ! Probably involve a lot of extra cost out here though, and would have to adapt it by extending the condenser under the van as Air Duster said.

Not really....
A real fridge won’t have a problem with the 110F to 120F temps.

I just mentioned the idea because it would reduce the load on the compressor and reduce the battery drain. But it isn’t required.

Bits like 12V Danfoss may be a problem too.

Remember you also can go with an inverter. Small sine wave inverters start at $100 US dollars. A 600W peak version can be had for $150 to $200 US dollars. Then you can just use an off the shelf table top fridge without modifications.

And you would get an added benefit of having access to AC power in your van. That is something that always comes in handy here and there.

[Brian_UK]

Bear in mind that with a caravan fridge, Electrolux I think, you can get three way power sources.

Unit is absorbtion powered by LPG, 12vdc or 230vac and they have a small flue that is fitted through the side of the vehicle.

edit

Do a Google with - electrolux caravan fridge - on the UK only and you'll find lots for sale, even on EBay.

[fridge doctor]

You are absolutely correct Brian, Electrolux are the manuf of the 3 way power source apsorbtion 'leisure' fridge, and i thank you for your continued interest. Realistically however, I don't see much prospect of getting one in Cyprus, althoug given my latest round of experiments with the PJ cooler, (little better than useless) I am definitely leaning toward more conventional refrigerating methods.

[Brian_UK]

Sorry FD, I forgot all about your location.

In that case try a boat yard or chandlery if there any about. Someone may be changing their fridge on board and have an old one to clear out - you never know your luck.

[jinxycat]

Q. but the temp in the back of my van during the day is between 35-45C, and the unit has had little effect.

which ever way you go really you should solve this part, if only to increase efficiency, ok absorption wouldn't care too much, but they can be funny about being jiggled around all day, i hear the fix is to lay them on a particular side for a bit to let all the good juices to find their way back home, and you end up running a gas flame or large heater in the back of the truck, vapor compression on 12v and 12v extraction fan maybe, ps you could reverse cycle it if you had soup and cool your van. lol

[750 Valve]

If you work on medium to large commercial heres an idea.
Get yourself a small esky, install a small bare pipe copper tube evap with a danfoss txv and a size "00" orifice - make the txv the same refrig as you commonly service (ie A/C mechanic - R22, fridgy - R404a) or keep a spare one in the van, use a schraeder valve as a liquid line connection point using a flex guage line to whatever you're working on, the suctions a bit harder, I'd do 2 x 1/4" connections or 1 x 3/8" and use 2 old guage lines and hook into suction side of the equipment.
For me as i work on supermarket racks with 3/8" access ports its easier, 1/4" liquid - 3/8" suction, you can even stick an epr on it to keep desired temp - not necessary if hooking into an A/C. All this with 2nd hand equipment, but its easy to make and will keep all your food cool on the job - not in the van and you can have a sandwhich and a cool drink in the plantroom or on the rrof as you sweat. When you're done, pump her down and put her in the car, the additional load on the equipment is negligable - like 200w or so.

[PaulZ]

Hi FD
Another make of compressor type car fridge is WAECO.
I have one and it sits in the back of my ute with a canopy and it will even freeze if you need it. It has no problem even on 45oC days.
They have a Danfoss compressor.
Paul

[fridge doctor]

Thanks fella's, more food for thought there noticeably from the southern hemisphere where it's getting a bit warm ! 750 valve - brilliant idea, not feasible for me, but love the innovation

Regards
Trevor

[Gary]

Generally, a pelt (thermo-electric) drops the temperature about 22K/40F. You can double this by stacking identical pelts, in effect cascading them.