Thread: Has anyone fitted temp control unit to an Engel?

Well, I used it over the Australia Day Long Weekend (I was away for about 5 days) and found the temperature control was much improved.

However, because of where the temp probe is located vs. the location of the Engel fridge thermometer probe, there was a bit of disparity. One can put an offset into the controller to match the readings but that wasn't the problem.

I've mounted the temp probe next to the fridge's thermostat and behind the white plastic cover at the compressor end.

What I'm now considering is drilling a hole at bottom of the white panel fitting a small computer fan behind the hole. I'll draw air from the fridge interior though this hole. At the top of the panel, I'll cut a series of slots to allow the air to exhaust back into the fridge.

I'm hoping this will better distribute the "coolth" in the fridge.

I'm not sure if I should draw from the top or the bottom. Comments welcome.

Originally Posted by CraigE

Hi,
I have been doing a bit of reading about changing the setup on an Engel from set thermostat control to temperature thermostat control. It makes a lot of sense and should have been done this way all along. As most of us that own these know the set thermostat is not the best type of control, especially in hot areas where you may set the setting to say 2 on a hot day and due to temps dropping overnight end up freezing items you dont want to........................................

I must be missing something here. A thermostat is a temperature controlled switch. It turns on at a set temperature and turns off at a set temperature (differential). It's not rocket science, usually some sort of bi-metal strip coiled up or fluid expansion/contraction device to operate a mechanical switch. Why does its operation matter whether it's day or night ? Sure there are better efficiencies with cooler ambient temperatures and using fans to remove excess heat from the condenser improves efficiency especially with high ambient temps so why is the thermostats operation dependant on ambient temp ? The thermostat is inside the fridge and turns the compressor on/off according to this temp and not the outside ambient temp ?

We run two Engels in the OKA, one MF35 which is probably about 20 years old as a fridge with an attached 'cool zone' as a crisper and a MF17 used as a freezer. An external digital thermometer is connected to each. The fridge is set at a nominal 2 degrees C and the freezer at a nominal -4 degrees C. Once settled down (ie warm contents cooled) the temps vary by about plus or minus 2 degrees C depending on day or night ambients which can vary between zero and 40 degrees C and I reckon this is more about insulation efficiencies and getting excess heat away during the day.

What am I missing here ?

Deano

Ron,
Can't work out exactly where you are going to drill a hole inside the fridge,but whatever you do don't damage the evaporator.Yours is probably the gold one,the best one they ever had.Once damaged it is a throw away

Remember too, the original t/stat operates on evaporater temperature,not air temp.Using evaporator temperature is the best way for a cabinet to work,particularly if it is not forced draught.To do the same with an electronic controller is a PITA to set up,can be done but not good practise.You can use an electronic controller in the air,but finding the best place for the sensor in the cabinet,and the best settings is guesswork.Also setup so there is not short cycling is also important.

We use hundreds of electronic controllers,check the amp rating on the switching contacts,guessing you have done that.

Why not just fit the original t/stat,i am pretty sure they are readily available and work well.I have trend logged both my 28 yr old and my brothers 30yr old Engle and have found the temps to be very good,even with changes of ambient temps during the night.if the thermostat is turned up during a hot day,products will probably freeze once the ambient drops during the night and the refrigeration system in the cabinet catches up.I set mine and leave it,never had an issue.

The fans are a very good idea,but probably only needed during periods of high ambient temps.If the head pressure is too low during cool ambient temperatures,issues can occur,and pull down rates extended.Also power is being used for no gain.

The main issue i have find using Engles is the cabinet insulation is not great.In hot weather i make sure mine is in the shade,out of the vehicle if possible, and cover the cabinet,being careful not to restrict airflow over the condenser,with a wet towel,if possible.Also make sure the cabinet is on a hard surface so the airflow from low down under the condenser is not restricted.

Hi Paul,

The original t/stat still works but I did find I needed to adjust the setting between day (when the Rangie is mostly closed up and the temp in the car is 45+ deg C) and night time. My fridge has the slight extra insulation of a transit bag. I suspect the bag's shade cloth covering the vents on the fridge doesn't help circulation.

It's impractical to remove the fridge when camped but it could be done. It's a pig to lift out from between the back of the left rear passenger seat and the storage drawers. It has to come out through the left passenger door over the seat. I put a towel over the car door window to put the fridge in shade for most of the morning.

The panel I am thinking of drilling pops out quite easily and is a cover over the thermostat bulb and pipework where it exits the fridge. See following pic taken from the 'net. My electronic sensor thermistor is behind that central plastic panel and is next to the thermostat bulb. I was going to tape it to the bulb.



I am not a fridgie so I don't understand how head pressures impact on refrigeration (I see some Googling coming up). I see the same thing is mentioned in the P38A workshop manual in reference to the condenser fans coming on, either at full speed or half speed - or not at all, only under certain conditions of A/C pressure.

My plan is to improve ventilation around the compressor area - it is restricted. I'll take some pics tomorrow and add them here. My Engel sits on a hard ply floor over the wheel well, not on carpet. I was going to drill some holes through the ply so that air can flow more easily.

When I was camping last, I was shown another bloke's set up where he draws air over a dampened Chux cloth - much like an evaporative cooler - to cool the air before passing it over the condenser.

Finally got time to do my mod.
My controller was shot.
The fridge would run continuously, never cycling off.
I found that if I disconnect the plug for the thermistor, it would turn the compressor off.

I used a Sestos D1s-2r-24 controller.
rated at 12-24 volt AC/DC.
This controller has a 10 year memory so long periods of disconnection should not be a problem.

A new rocker switch was installed for on/off, the red and orange wires

Additional k-type thermal sensor was installed in the original location.
To power the controller I tap into the red wire + and ran a earth to a screw on the chassis of the fridge.
This powered the controller but the fridge would not turn on unless a diode was place between the blue and purple wires as per original configuration.

The brown and black wire originally had the variable resistor and 2 resistors in parallel in its circuit.
these were replaced with 1x 12K 1watt resistors in parallel.


So far I have found a set temp of 2 degrees will give a compressor run state until 0.8 degrees and a restart of 2.3 degrees.
Run time is 1min 35 sec with downtime of 3min 55 sec


So in summary
red/orange--on/off switch---red to power the controller.
brown/black --3x 12k 1w resistors
blue +/ purple - -----led diode.


Original thermistor wires were cut and controlled by the alarm contacts.


I also replaced the fan (24v dc) with 2x 120mm fans wired in series.
Fan supply was also 17v dc at the time of testing.


the attached picture of the terminals with wires connected is not quite the finished product.
originally I powered the controller from the led supply.
this proved no good as when connected to 12v in the defender,the volts dropped to around 7.
The controller is now powered from the red switch wire and seems to working fine on 12v dc.

Reviving this Post.
Hi all reviving this post as I finally have some of the parts I need, fans, thermostat controller.
From what I can gather between Rons instructions and the GPSOZ instructions is I have to make a PCB board up and wire into the circuit.
Now some of the numbers posted in the GPSOZ page seem to be outdated.
Can anyone advise on updated numbers from Jaycar as DSE dont stock them or similar as cannot find any reference to these numbers or can a pre made board be bought to these specs?
H5605 pcb (you only use 1/2 of this)
R4460 capacitor
R4705 capacitor
Z6552 regulator
Z3304 Rectifier Bridge
H2870 Box

Has anyone actually made one up and if so do you have any photos? If so can you please post?
This will be my first venture into making up a board like this, so need some clear instructions, though have replaced a couple.
Also has anyone done this for the 240v side as I also have a suitable 90-240v thermostat controller.
Cheers
Craig

Originally Posted by CraigE

H5605 pcb (you only use 1/2 of this)
R4460 capacitor
R4705 capacitor
Z6552 regulator
Z3304 Rectifier Bridge
H2870 Box

DSE nos. followed by equivalent Jaycar nos.
H5605 - use some veroboard HP9540
R4460 2500uF electrolytic capacitor. Use 16volt minimum, say RE6238 (105 deg C rating)
R4705 capacitor - use a polyester 0,22uF RG5150
Z6552 7812 regulator, Jaycar ZV1512
Z3304 Rectifier Bridge, type BR105 Jaycar ZR1320
H2870 Box - just have a look for some Jiffy Boxes - maybe ones with mounting flanges HB6016

I didn't make up a PCB. I just bolted the bridge rectifier to the case and ran wires to it. I didn't think the extra bits to rectify and smooth the DC supply were necessary to just run the fans. I'll need to find the thread again to see what I wrote.

However, mine isn't running the digital controller when on 240v. I never use the fridge on 240v. I might look at doing that just for completeness sake.

If you want to use a PCB, one would normally design and etch the board to remove the unwanted copper. I suggest you look at using Veroboard. It has strips of copper and is pre-drilled on a 1/10" spacing.

https://www.google.com.au/search?q=v...w&ved=0CCMQsAQ

To break up the strips, one can use the genuine tool or do as I do - get a 3-4mm drill and use it to cut away the copper.

See [ame]https://www.youtube.com/watch?v=x4p5wD2wMjo[/ame]

I'm interested also, I have two fridges to convert. ......