Hi
@DWWood,
there are many ways to improve the performance of 3-way fridges. Adding a fan is only one of them.
If you search through the forum you will find that this topic has already been raised and discussed many many times.
But briefly, the other main improvements are:
1: ensure the top and sides of the fridge are completely sealed from the back compartment.
2: consider adding a shade cloth to the off-side of the van to ensure the sun does not fall on the vents and thus ensure cooler air entering the compartment.
3: ensure there is no gap between the body of the van and the cooling fins. i.e, most of the cool air coming from the bottom vent flows through the cooling fins. Later Jaycos have now added a piece of sheeting to do this.
4: consider adding an internal fan to efficiently circulate the air inside the fridge. This also reduces or eliminates frost buildup on the cooling fins which reduces cooling efficiency.
With these basic improvements and a few others, I don't have any problems running the fridge at 4-6C and the freezer at -15C in summer on days of around 40C
Now, $130 seems like a lot of money. A much cheaper alternative is to buy a good, quiet, and efficient fan online for about $20 and head off to Jaycar and buy a Normally Open thermostat and some cable and a fuse for a little over $10. You can pick the thermostats up on eBay for around $1 and they come in 5C increments. I use 50C.
I would have a few issues with fitting this device:
1: What is the current draw? The fan I have is a 120mm BeQuiet PureWings 2, draws only 90mA and shifts 51.4cfm. It was a little over $20 from PCCaseGear in Melbourne. It is way better that the standard fans available at Jaycar etc.
2: How much noise do these fans make when running? There seem to be three small fans and look to be less than the normal 120mm fans, they will also be spinning faster than a 120mm fan. More noise, less reliability, less efficiency, higher current draw.
3: the 40C thermostat is too low. In 40C heat the fans will be turning on and staying on regardless of whether the fridge is running. Come home, a few hot days with the van parked and come time to take it out and the fans have flattened your battery.
4: This plate has almost completely blocked the top vent. If the fans fail, it will get very hot in the rear compartment and the only solution will be to remove the entire assembly.
5: The switch is only accessible by removing the external vent. If you look at the flimsy catch that holds the vent in, it is not designed to be removed regularly. Break the spiggot and you have to replace not the vent, but the external frame.
6: My main concern. The back compartment serves TWO conflicting purposes.
One is to create airflow to coll the condensation fins at the top of the fridge. So, good airflow from the bottom vent passes over the cooling fins and exits through the top vent. This creates a chimney effect when the top vent is above the cooling fins. NOTE, that on camper trailers this is not possible and the top vent is about level with the fins and thus cooling is not as efficient. In older camper trailers, the top vent was inside the van cut into the benchtop and they worked better BUT that is now illegal due to improved gas regulations.
The other is the boiler, which for efficiency should be kept hot and NOT cooled.
I experimented with one and then two fans. The performance with two was less than with one because the second fan, fitted over to the right ended up drawing HOT air from around the boiler (and cooling it) and then drawing it past the cooling fins.
If you look at the assembly. They are mounted mostly towards the right. The hottest part of the condensation fins is actually on the left.
I hope this helps you make an informed decision.
Apologies for the long posting. This is one of my pet subjects. I wanted to avoid having to change to a compressor fridge PLUS the extra battery and 200W of solar panels to keep the power up to it.
cheers
Mike