Trying to find a fridge issue with inconsistent function

[SailorMcCruise]

Hello there,
I am currently taking a friends boat south for Hurricane Season protection and unfortunately the fridge is not really working properly.
The compressor is a Danfoss BD35F the control unit a Danfoss 101N0210.
The whole unit a Frigoboat Frigomatic Madrid 35 F.
Now what happens is that the fridge sometimes works supernicely and keeps everything nice and cold ( even freezing stuff inside the cooling element ) and then barely working again.
I bridged the potentiometer to see if the unit will then work full power but no change. The compressor is running and warm to the touch, the fan working as well. Usually I would have guessed not enough coolant in the system but why would it be working sometimes anyway? Could the system be clogged? Anything I can still do to troubleshoot? Will be far away from any proper technician for some time I guess.

Thanks a lot for any tip!

[wingless]

Welcome to the forum.

Has a 12V LED been connected to the controller to obtain the Error Codes?

If so, what error codes are being provided?

[SailorMcCruise]

Hello, not that I know of. But I can try / look. Where would I find the LED or the connectors for it?

[wingless]

When I made mine, I used a standard T1-3/4 red LED and put about 1K Ohm in series, then connected as-shown in the link.

There are standard Faston tabs on the controller.

[SailorMcCruise]

Hello and thanks. i cannot seem to be finding the link? will look for a Led though, but I am afraid I’d have to take apart my VHF which I am reluctant to do

[Bean Counter]

Is the boat on shore power or mooring/anchor? I.e. is fridge running off batteries that need charging?

[SailorMcCruise]

The boat is on solar / generator power. battery is doing fine with a quite constant 13.5 V

[wingless]

Click on the words: “Error Codes” in reply #2.

[SailorMcCruise]

hm, so i do not have access to an led, but i connected a simple multimeter and switched it to resistance. i guess i should get flashing numbers then as well, which I did not. it showed a constant resistance of 0.06 on the 200ohm setting.

[s/v Jedi]

How to diagnose refrigerant flow:

with the unit running when it's working: stick you head inside the fridge near the evaporator plate and listen. You should hear a gurgling sound which is the refrigerant evaporating. Check the lines on the plate and the spots where the refrigerant line is soldered on. Is there ice forming on the plate in that spot or over a larger area?

Now when the unit does not work: stick your head in again and listen. When the gurgling sound is gone, take a hair dryer or heat gun and heat that area where the line is soldered to the plate. If this makes the unit kick back in to gurgling and cooling then you have moisture in the system, caused by a leak (often the O-rings when you have quick connect fittings and it's a couple of years old).

If this is the problem then the system needs to be checked for the leak location (replace O-rings, comes with spares), evacuated with a vacuum pump and refilled. During evacuating, use the heat gun to heat all over the evaporator plate, the lines and the compressor incl. the brass "bulb" dryer. This promotes moisture boiling out of the oil. You can hear the effect at the vacuum pump immediately as it begins to sputter as soon as you hit parts with moisture inside with the heat gun.

For filling: these systems should be filled by observation of the return line from the evaporator to compressor. Don't forget to bleed the hoses, then fill with system turned off to bottle pressure. Then close all valves and start system. Only add refrigerant on the low side (the cold return line) and fill so that this return line starts sweating. If it starts freezing, there is too much refrigerant in the system. This is fool proof and optimal fill level

[wingless]

Follow the instructions in the link to discover why the controller isn’t happy.

If getting an LED, resistor then connecting those per the manufacturer’s instructions is beyond the available skill set, then this first step along with all the next steps should be passed to a professional.

[Richard Kollmann]

Originally Posted by SailorMcCruise

Hello there,
I am currently taking a friends boat south for Hurricane Season protection and unfortunately the fridge is not really working properly.
The compressor is a Danfoss BD35F the control unit a Danfoss 101N0210.
The whole unit a Frigoboat Frigomatic Madrid 35 F.
Now what happens is that the fridge sometimes works supernicely and keeps everything nice and cold ( even freezing stuff inside the cooling element ) and then barely working again.
I bridged the potentiometer to see if the unit will then work full power but no change. The compressor is running and warm to the touch, the fan working as well. Usually I would have guessed not enough coolant in the system but why would it be working sometimes anyway? Could the system be clogged? Anything I can still do to troubleshoot? Will be far away from any proper technician for some time I guess.

Thanks a lot for any tip!

If after 20 minutes compressor Stays cool and no evaporator cooling follow these steps. If compressor does get slightly warm Run a new ground jumper wire from battery ground post to Danfoss module negative terminal. Compressor still does not run try the following.

1. Place jumper wire across thermostat terminals, Compressor still does not run.

2. Disconnect black fan wire from electronic module, Compressor runs replace fan. Compressor still does not run after fan ground wire is disconnected. If one of the 10 transistors in this fan fail it can cause module to prevent compressor from running.

3. Run correct size and correct polarity fused jumper wires direct from a fully charged battery to module in order to bypass all boat’s wiring. Volt meter readings are of no value, Compressor still does not run electronic module needs to be tested on another unit.

[SailorMcCruise]

Thanks for all the helpful answers. @s/v Jedi: that is the most elaborate description I ever got in a forum, thanks ) Since I lack most of the tools here on board, I‘ll have to wait til I arrive in Grenada
So since
I bridged the thermostat and the compressor runs and the evaporator gets slightly cold with no noticable icing at any part. just cold condensing water on surface.
That was the status quo when I took over the boat and it made me think there might not be enough coolant in the system until it suddenly sarted to get very cold for no apparent reason and now back to the warmer state also for no apparent reason.
Does the heeling of a boat have an impact of coolant flow,, if there is not enough coolant in the system?
@wingless: in my browser northing hints at the words containing a link. Also, obtaining an led and resistor is not about skillset here but merely about non existing shops.. thankfully one can resort to other means, like a multimeter instead of an led.

[Richard Kollmann]

Originally Posted by Richard Kollmann

If after 20 minutes compressor Stays cool and no evaporator cooling follow these steps. If compressor does get slightly warm Run a new ground jumper wire from battery ground post to Danfoss module negative terminal. Compressor still does not run try the following.

1. Place jumper wire across thermostat terminals, Compressor still does not run.

2. Disconnect black fan wire from electronic module, Compressor runs replace fan. Compressor still does not run after fan ground wire is disconnected. If one of the 10 transistors in this fan fail it can cause module to prevent compressor from running.

3. Run correct size and correct polarity fused jumper wires direct from a fully charged battery to module in order to bypass all boat’s wiring. Volt meter readings are of no value, Compressor still does not run electronic module needs to be tested on another unit.

Not knowing if the refrigerant circuit has been tampered with to where there is too much refrigerant or contaminates,I followed the normal direction of troubleshooting a Danfoss BD system of electrical faults that prevent compressor from running efficiency.

The nondestructive steps I listed would confirm compressor was running.
Thermostat and speed resistor were not at fault.
Three phase compressor interrupted pulse fault allowed compressor to run but too slow do to faulty Grounding.
Amperage of fan exceeding 1/2 amp signaling module to prevent compressor from running.
Eliminating all boat wiring as a cause of dirty power to module.

[sailon46]

I have the same setup in my Bene 51.4 and it was doing the same thing first two days good cold everything then the rest of my two weeks on the boat
Needed to buy ice which is hard to find in SE Carib. Found the problem with my trusty Fluke checking the voltage of the unit under load and surprise me the volts stayed around 12 v sometimes in the same run would drop to 7. The power cord from the board was rusted out at a splice under the floor boards. Good luck.
FYI Ernie on the Mary Jane