Troubleshooting Danfoss BD35 / 101N0210 unit where compressor fails to start

[SailorMcCruise]

Originally Posted by Richard Kollmann

IF new ground does not fix problem remove 2 seconds of small amounts of refrigerant with compressor stopped waiting 5 minutes each time after each start up test and try again.

If LED code displays 4 or 5 or 6 flashes every 4 seconds also run a new power wire with 15 amp fuse direct from battery to control module.

Thanks. How do I remove the refrigerant? With that bicycle type valve?

Thanks

[sailingchiro]

Originally Posted by Coolerking

There is NOT a start or run cap on secop/danfoss 12/24vdc. units

Thanks, I never did see one but didn't know if internal or? I honestly didn't know.

[Coolerking]

Originally Posted by SailorMcCruise

Thanks. How do I remove the refrigerant? With that bicycle type valve?

Thanks

Yes, depress the Schrader valve, just like you were letting air out of a bike tire.
Make sure compressor has been off for at least 10 minutes before you do it, as you want to be sure you have positive pressure there.

[thunderhoof]

For anyone looking to replace the fan itself, a 12 V computer fan works well. They are quiet, efficient and not expensive.

[Uncle Bob]

Hi, had a similar problem with mine a few months back, chatted with Pete from ozefridge who suggested the addition of a relay in the cooling fan circuit and voila all is good, thanks Pete.

[Pete7]

Originally Posted by Uncle Bob

Hi, had a similar problem with mine a few months back, chatted with Pete from ozefridge who suggested the addition of a relay in the cooling fan circuit and voila all is good, thanks Pete.

How would a relay help?

The fridge was working and now it doesn't. The boat is damp. Jedi has suggested the likely problem is corrosion in the connections, the boat is after all damp. Fitting a relay may help in that making new connections resolves the problem for a while. The problem isn't the fridge, but a damp boat causing corrosion.

Pete

[Richard Kollmann]

Originally Posted by Uncle Bob

Hi, had a similar problem with mine a few months back, chatted with Pete from ozefridge who suggested the addition of a relay in the cooling fan circuit and voila all is good, thanks Pete.

If you install a relay it eliminates the safety factor Danfoss designed into the system to prevent system damage due to excessive high pressure by limiting fan to 1/2 amp. When the trouble LED sends a two flash code replace the fan as all of the 6 LED code flashes are intended to keep these system reliable. Installing a relay on fan is like an electrical circuit without a current limiting fuse or breaker.

[Uncle Bob]

Originally Posted by Pete7

How would a relay help?

The fridge was working and now it doesn't. The boat is damp. Jedi has suggested the likely problem is corrosion in the connections, the boat is after all damp. Fitting a relay may help in that making new connections resolves the problem for a while. The problem isn't the fridge, but a damp boat causing corrosion.

Pete

Pete, the cooling fan was running but the compressor would attempt to start and then wouldn't. The advice received was that the fan controller was conflicting with the compressor and they weren't playing nicely together, the addition of the relay in the cooling fan circuit bypassed this conflict and to date (touch wood ) all has been good.
As to the damp boat, I would suggest that sufficient forced air ventilation would go a long way to eliminating this problem. It is neither difficult nor expensive yet yields great results.

[Richard Kollmann]

Originally Posted by Uncle Bob

Pete, the cooling fan was running but the compressor would attempt to start and then wouldn't. The advice received was that the fan controller was conflicting with the compressor and they weren't playing nicely together, the addition of the relay in the cooling fan circuit bypassed this conflict and to date (touch wood ) all has been good.
As to the damp boat, I would suggest that sufficient forced air ventilation would go a long way to eliminating this problem. It is neither difficult nor expensive yet yields great results.

It is always a risk and reword situation when you tamper with proven devices designed to prevent catastrophic equipment failures. The Danfoss BD compressor insures system's long life by testing six electrical function at control module during compressor start. The relay to reduce excessive fan amperage is much like those days when people put a copper penny behind a fuse that kept blowing.

[Coolerking]

The fans used on these systems draw .24 amps, they are 12vdc regardless of the input voltage to the unit.
When they begin to fail they begin to draw more, and this often will cause the start sequence to be interrupted.
I have replaced many dozens of them over the course of the last 17 years.
An easy way to check is to just disconnect the fan and see if the compressor will start, in fact, the compressor is so quiet that the fan noise can make it really hard to hear the compressor run.

[SailorMcCruise]

Hello people.
Sorry I could not answer earlier. Was is a very remote spot, enjoying life without a fridge
So:
I did another test with proven to work thick cables running directly from the battery - no change.
I did release refridgerant with the schrader valve - no change.
Since "Jedi" mentioned corrosion: Is there any other element that coould be afflicted by corrosion inside of the element ( it looked quite ok to me on visual inspection - just the outside of the compressor is rusty at places )

[wingssail]

Originally Posted by SailorMcCruise

Hello people.
Sorry I could not answer earlier. Was is a very remote spot, enjoying life without a fridge
So:
I did another test with proven to work thick cables running directly from the battery - no change.
I did release refridgerant with the schrader valve - no change.
Since "Jedi" mentioned corrosion: Is there any other element that coould be afflicted by corrosion inside of the element ( it looked quite ok to me on visual inspection - just the outside of the compressor is rusty at places )

Now that you have done all this testing and inspections (and wiring testing) and reported it all to us, I am going to venture to say that the compressor is bad. From every thing you describe the electronic module is doing is thing. The compressor just isn't starting.

I've had these exact symptoms with an exactly similar system, (BD35 /101N0210, air cooled condenser, etc, in June 2019, with a 9 year old system.

In my case I noticed the compressor attempting to start several times, then finally starting, for several days before it finally stopped for good.

I replaced the entire refer including the evaporator mainly because my quick connect fittings had been damaged previously (during the original installation) and I knew that I could not connect a new cooling unit to the existing evaporator. It gave me an opportunity to R&R the box and insulation.

The report is here: WINGSSAIL - Cruising Log of Wings - Serendipity 43 - Fred Roswold & Judy Jensen

[Zencra]

Originally Posted by Richard Kollmann

If you install a relay it eliminates the safety factor Danfoss designed into the system to prevent system damage due to excessive high pressure by limiting fan to 1/2 amp. When the trouble LED sends a two flash code replace the fan as all of the 6 LED code flashes are intended to keep these system reliable. Installing a relay on fan is like an electrical circuit without a current limiting fuse or breaker.

I'm getting a 2 flash code without a fan connected. I run my fan 24/7 direct wired.
I can hear compressor kick for half a second and stop, 10 or so seconds later it tries again. I have 13.1 volts at controller. I've found a fellow in Melbourne, Australia that builds controllers at half the cost, he also sell originals so I'm getting a few brought over here to Portugal for spares.