RE: Fan cooled trailblazer

Yeah, I will actually do that sort of test, as in a matter of a week or 2 will be back on the road camping full time for the next 6 - 8 months, which I will able to afford to have more time to do the more intensive testing. Problem is, dont have the internet while travelling to post results, so will try to get results online asap.

I would assume tho, if it takes half the time to get to 0 deg. ,the cycles of the fridge would have to be the around the same time as before, but only running half the time in that cycle. Sound right???

Sounds like it will be a really hard test as there are a lot of variables (besides fishing, drinking, sleeping etc.) as it will be over 24 hrs, battery voltage at beginning, amb. tempertures etc. - oh well see how I go.

Milo,
The ratio doesn't crossover like that, my rough figures I gave before. My ON cycle is about half hour[ doesn't seem to change much regardless of ambient] the OFF time shortens > 30oC. From my measurements I found the 25% dutycycle TB quotes is about 25oC over 24hrs.

If you have time, build a sock for the lid.......helped me a lot[25mm CSF Clarks - blue grade or Armaflex = $$$]

Have a great trip and please post when you get back.

cheers

The TB has its condenser fitted to the large rectangular sides. The fan fitted to the compressor cavity would help to cool the compressor. As the Engel condenser is within the compressor cavity, I expect the fan would help as you have proven.

cheers

Rob,

Are you talking to Milo or me?

cheers

Sorry, Milo it is.
I want to fit a fan to my trailblazer so any info would be great.

Rob

G'day Rob,

I bought the computer fan from Jaycar $15 ish, about 100mm dia or so, about 20mm thick square casing 12V.

Mounted it btween the casing and compressor (just fits!), drilled series of 20mm holes around where the blades are, than bolted on.

The wiring was more tricky as it sounds there slightly different in different models. But mine was (early 90's mod) to the black box which is mounted on the wall of fridge, which along the bottom has left to right, C , T , # , F , # , + , -.

Where the '#' are, is where I hooked mine into, being neg or pos, - cant remember, but by hooking to those ppoints allow the fan to only activate when the compressor is on (obviously the only time it needs blowing on).

The only other thing that I did different was mount in a switch (standard 240V architrave elec. switch), beside my similar freezer on/off, to be able to turn it off/on as my desire. As I found the fan to be not the quietest out there (not that I experimented with different fans), and with the wind sucking thru the holes made, was noisier than expected, thus when sitting around the campfire in the cool of the night with hearing nothing but the fire crackling, did not want to here a fan kick in, also not needing it if weather is cooler like at nite or down south.

Hope this helps...

Wok, do you not have freezing capacity with you TB? As looking at the pictures you only have the one thermostat control?....

I was also wondering why you had so much extra room in your motor compartment, - is it only 12V? Mine has a 240V conversion box down in that right hand corner, as there was no chance to do what you have done!!

Still dont quite follow what your doing with the lid tho?

Milo, my TB is 'no frills' , I built an external power supply from bits I had. In the rare time I am at caravan park I can charge the aux battery as well as power the TB via the Andersons.
Yes, only 1 thermostat.I built a spacer board that fits a third up from bottom so I can freeze the bottom[sort of works] The pickup is at the top with the thermometer pickup at the same level[where it is the warmest]

I used a blower because its directional and can 'compress' the cavity. It could be positioned in other locations.It is mounted with 2 bolts.Checkout the smaller blower from Jaycar..could run direct from the controller & heaps quieter than the one I used [hindsight] there is enough air flow from the baby.

My tests showed the lid was the weakest part of the TB[w.r.t heat gain].I set out to remove [a]metal-metal paths [b]metal-cavity path
For [a] : the hinges were repositioned to the back, I fitted a strengthing bar across the back; the screws holding the inner shell were removed[no longer needed]
For [b] : the Al inner shell was removed

The sock is the blue bit; I used sprayon glue to make it. I found that it was not performing to my satisfaction[after settling down the surface of the sock was still significantly cooler then ambient]...hence the other mods.

Note: my lid is removable, ie slide-on. In hindsight I should have welded the corners when the outer shell was naked.......duh...duh

My conclusion: The lid mods were more effective in improving the TB then the fan [ in agreement with Nudenut on this point]The hassle with fridge tests is the time factor, I found it took up to 6hrs before the thermal gradients were established and I could get repeatable measurements.

Talking too much!

cheers