12v compressor fridge runs constantly

mrtoomanytoys

mrtoomanytoys

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So in preparation for my next visit to the boat in a week's time. I am delving into an issue I uncovered while it was out of the water..
As I didnt have shore power, the fridge was on the battery bank. Despite changing the thermostat settings from min to max. At no point did the compressor stop running. (Works exceedingly well).
The installation does seem to be a bit amateurish. Insulation on pipes and box is a bit mish mash.. the compressor pack was screwed down with a 3 different screws, (minor thing, but just reeks lazyness)
All I can determine is that it is a retrofit kit with danfoss compressed and control box.
Obviously I need to check how the thing is wired up, there is no paperwork with the boat to support this..
I have a generic diagram from the internet on the 101N0220 controller.. so will start there with my multi meter..
Any further info will be a bonus.
Cheers
 
MoodySabre said:
When my car aircon stopped getting cold it needed re gassing. I don’t think the plate will get cold without gas.
Click to expand...
Car air con and fridge have different gas pressure. Fridge is a lot less gas also a much lower pressure...I'm not saying it's not the thermostat...but a slight reduction/loss of gas will still make the plate cold but probably not sufficiently cold enough to activate the stat...disconnection of the stat as suggested by Graham376 will obviously stop the compressor but that doesn't necessarily prove the stat is faulty.
Problem with aircon and fridges is you need the equipment to test, if you haven't got it and you spend €40 on a stat only to find it is the gas.
 
billskip said:
Car air con and fridge have different gas pressure. Fridge is a lot less gas also a much lower pressure...I'm not saying it's not the thermostat...but a slight reduction/loss of gas will still make the plate cold but probably not sufficiently cold enough to activate the stat...disconnection of the stat as suggested by Graham376 will obviously stop the compressor but that doesn't necessarily prove the stat is faulty.
Problem with aircon and fridges is you need the equipment to test, if you haven't got it and you spend €40 on a stat only to find it is the gas.
Click to expand...

Most stats are a 2 wire on/off switch so can be checked with multimeter.
 
Graham376 said:
Most stats are a 2 wire on/off switch so can be checked with multimeter.
Click to expand...
Agreed...but disconnection puts the circuit in the "off" position, it is possible the stat is not getting cold enough because insufficient gas in the system....I'm not saying it's not the stat, but it could be los of gas.
 
Been a bit busy..
Certainly seems to be getting plenty cold.. (had put ice in a box in the fridge and had ice cubes for a couple or 3 days. Previously)
Will check the t stat operation.
Need to check the wiring as the rest of the install is quite amateurish..
I had other things on my mind last time down.. 🤣
 
Stat appears to be operating correctly.. with mulitmeter

On a wiring diagram from internet, there should be some resistor to P..
Brown wire was to bottom. (Stat is brown & black) 1000006246.png1000006259.jpg
 
mrtoomanytoys said:
Stat appears to be operating correctly.. with mulitmeter
Click to expand...
Is that testing the stat capillary end in ice? Or just switching it on and off?
The sensor at end of capillary tube needs to switch it on or off not the knob you twist......I still think it's lack of gas/refrigerant...but, but,... p I think you say the plate gets very cold, which would indicate the stat/capillary faulty.
 
billskip said:
Car air con and fridge have different gas pressure. Fridge is a lot less gas also a much lower pressure...I'm not saying it's not the thermostat...but a slight reduction/loss of gas will still make the plate cold but probably not sufficiently cold enough to activate the stat...disconnection of the stat as suggested by Graham376 will obviously stop the compressor but that doesn't necessarily prove the stat is faulty.
Problem with aircon and fridges is you need the equipment to test, if you haven't got it and you spend €40 on a stat only to find it is the gas.
Click to expand...
Air con and fridges have the same pressures if using the same gas. Less gas doesn’t mean less pressure if gassed correctly. Volume of the system internally defines how much gas you need, pressures are the same at similar temperatures.
If the op is keeping ice in it then it looks like it is working correctly. The external air temperature is a factor, bad insulation will leak heat in to it forcing the compressor to keep working hard and with the stat turned to reallly cold it won’t be able to pull the temperature down enough to switch the compressor off.
 
mrtoomanytoys said:
So in preparation for my next visit to the boat in a week's time. I am delving into an issue I uncovered while it was out of the water..
As I didnt have shore power, the fridge was on the battery bank. Despite changing the thermostat settings from min to max. At no point did the compressor stop running. (Works exceedingly well).
The installation does seem to be a bit amateurish. Insulation on pipes and box is a bit mish mash.. the compressor pack was screwed down with a 3 different screws, (minor thing, but just reeks lazyness)
All I can determine is that it is a retrofit kit with danfoss compressed and control box.
Obviously I need to check how the thing is wired up, there is no paperwork with the boat to support this..
I have a generic diagram from the internet on the 101N0220 controller.. so will start there with my multi meter..
Any further info will be a bonus.
Cheers
Click to expand...
Ah! Out of the water, if you have a water cooled condenser thru the hull then it isn’t getting cooled enough to work properly.
 
Beneteau381 said:
Air con and fridges have the same pressures if using the same gas. Less gas doesn’t mean less pressure if gassed correctly. Volume of the system internally defines how much gas you need, pressures are the same at similar temperatures.
If the op is keeping ice in it then it looks like it is working correctly. The external air temperature is a factor, bad insulation will leak heat in to it forcing the compressor to keep working hard and with the stat turned to reallly cold it won’t be able to pull the temperature down enough to switch the compressor off.
Click to expand...
A simple car aircon according to Google quote...
gerant used. Generally, low-side pressure should be between 30-50 psi, while high-side pressure should be around 150-250 psi

Fridge....quote...Generally, low-side pressures are relatively low (around 1-5 psi) while high-side pressures can be significantly higher (150+ psi).

Spot the difference?
 
billskip said:
A simple car aircon according to Google quote...
gerant used. Generally, low-side pressure should be between 30-50 psi, while high-side pressure should be around 150-250 psi

Fridge....quote...Generally, low-side pressures are relatively low (around 1-5 psi) while high-side pressures can be significantly higher (150+ psi).

Spot the difference?
Click to expand...
Oh dear me! What temperature? What gas?
 
Beneteau381 said:
So did I and know that pressures vary at different temperatures.
Click to expand...
Maybe so,
(where were you in Venezuela? )
It's not what I said, what I said was the pressure are different in an aircon than a fridge..believe Google or not, the low pressure (suction) on a split aircon unit can be 70psi, and in a car 30 psi, the low pressure in a fridge will be usually less than 5 psi...
This information is all over YouTube and Google, I'm not trying to suggest you are wrong I was and still am simply saying the pressures are different in aircon and fridges...
 
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