Refrigerator issue Danfoss bd35

[smcboating]

Hi have a dometic tundra marine fridge that uses a Danfoss bd35 compressor and a Danfoss 101n0210 controller. It’s symptoms are that the fan is running, the compressor is not running and it’s not cooling. I’m getting the 5 flash led trouble light. I have researched some threads on this forum and done the following:

Checked the source voltage-this fridge came with a 100v converter. So I have the fridge in my garage on my bench running off this. It seems to work right. The symptoms are the same running off this converter or 12v. Without the fridge running it seem to put out 24 volts. (Tested at the controller) I can pull a battery out of my boat, charge it and run it off this if needed.

Also done the T-to-C jumper wire to by pass the thermostat. No change

I have pulled off the fan positive wire and this did not help

I tried disassembling the thermostat and checked the connections and they seemed fine although the wire that attaches to the freezer is a little rusty. I did not want to break it so I left it alone.

The fridge worked great for many trips over the years. I’ve always been a little concerned that the buildout for it doesn’t have enough venting. I’m guessing it might have had a thermal overload which affected the controller. Maybe resistance in the original wiring on a hot day trying to run it to hard did something to the controller circuits. Thinking that is why the fan runs constantly and the compressor does not turn on.

While I was bench testing it the compressor did come on once and it was cooling at that point. Not sure what I did to make this happen other then moving the module around some.

Not sure what else to check. If anyone has any ideas that would be a tremendous help.

Also I see many different model numbers of these controllers for the bd35 compressor. I’m wondering if I can use a different part number. As I mentioned above mine is a 101n0210. I’m seeing a 101N0212 ($135)Danfoss(brand new)that looks the same and says it runs the bd35. Or the 101N0320($80).

https://www.ebay.com/itm/39321643428...oAAOSwGgdfyNxK

Thanks for any help you guys are a great resource and much appreciated

Sam

[OzeLouie]

Originally Posted by smcboating

Hi have a dometic tundra marine fridge that uses a Danfoss bd35 compressor and a Danfoss 101n0210 controller. It’s symptoms are that the fan is running, the compressor is not running and it’s not cooling. I’m getting the 5 flash led trouble light. I have researched some threads on this forum and done the following:

Checked the source voltage-this fridge came with a 100v converter. So I have the fridge in my garage on my bench running off this. It seems to work right. The symptoms are the same running off this converter or 12v. Without the fridge running it seem to put out 24 volts. (Tested at the controller) I can pull a battery out of my boat, charge it and run it off this if needed.

Also done the T-to-C jumper wire to by pass the thermostat. No change

I have pulled off the fan positive wire and this did not help

I tried disassembling the thermostat and checked the connections and they seemed fine although the wire that attaches to the freezer is a little rusty. I did not want to break it so I left it alone.

The fridge worked great for many trips over the years. I’ve always been a little concerned that the buildout for it doesn’t have enough venting. I’m guessing it might have had a thermal overload which affected the controller. Maybe resistance in the original wiring on a hot day trying to run it to hard did something to the controller circuits. Thinking that is why the fan runs constantly and the compressor does not turn on.

While I was bench testing it the compressor did come on once and it was cooling at that point. Not sure what I did to make this happen other then moving the module around some.

Not sure what else to check. If anyone has any ideas that would be a tremendous help.

Also I see many different model numbers of these controllers for the bd35 compressor. I’m wondering if I can use a different part number. As I mentioned above mine is a 101n0210. I’m seeing a 101N0212 ($135)Danfoss(brand new)that looks the same and says it runs the bd35. Or the 101N0320($80).

https://www.ebay.com/itm/39321643428...oAAOSwGgdfyNxK

Thanks for any help you guys are a great resource and much appreciated

Sam

Firstly a 100watt AC-DC converter is very marginal and may be your problem. The following should confirm but the fact that it did a run is encouraging......

Compressor fails to start or cuts out prematurely:

By far the most common problem DC refrigerators have is the 12VDC power supply, and not the actual compressor or MDM itself!

To explain: All of these DC compressors have a ('black box') Motor Driver Module, (MDM) which inverts the supplied DC power into 3 phase AC power to drive the 3 phase AC compressor motor. These MDM's are of two very different types, DOL and Soft Start.

The DOL (Direct on Line) module causes a massive current inrush (can be up to 7-8 times run rate) as it tries to take the compressor from stationary to run speed virtually instantly while the Soft Start MDM slowly starts the compressor without any inrush current..

If the voltage drops away too much at a start attempt or when running, the MDM's low voltage cut out prevents the module driving the motor from starting or running.

This shut down because of a poor power supply, is usually due to either a defective, or faulty battery, battery to MDM wiring, or faulty devices along that circuit like bad *spade terminal connection, switch or overload. (*Specially - & + on the MDM)


If unit won't run, below is the easiest and industry recognised way to identify if voltage drop is the problem or if the MDM is faulty..



Voltage drop test: (Above)

Using a good multi-meter connected to the negative and positive terminals (- & +) on the MDM as shown above, read the voltage before and when the compressor starts or attempts to start.

The voltage reading with no load, before the compressor starts is meaningless but do note that no-load voltage.

Next, continue to monitor the voltage as the compressor starts or attempts to start. If this voltage drops away by say a volt or more or below 10 volts then that is confirmation that most likely the power supply is the problem and that the compressor and MDM are not at fault. Again with multi-meter, check again as above, from MDM back to the battery, testing at each terminal access etc.

Thermostat test:

Terminals C & T are the thermostat switch connections. (Bottom and third from bottom terminals) If there is adequate DC power to the MDM but the compressor will not start or attempt to start, it may be because the thermostat (switch) is faulty.

To check simply bridge the terminals C & T and if the compressor runs then the thermostat is faulty. If an older system with mechanical thermostat, consider replacing with a digital type for far more accurate control and temperature read out.
​

Fan Corruption:

Most DC refrigeration units use small fans. If the fan draws greater than half an amp (6 watts) the MDM will shut the system down. These fans are also driven via their own internal micro processor, a processor that if faulty can corrupt the MDM, therefore if fault persists try disconnecting the fan and if the compressor then runs, switch off and replace the fan.. most likely a type 100-25 12VDC., 2.5 to 4.0 watts

[cr180]

I also have a Tundra. Have had several problems, but not your problem. None the less have gotten familiar with the Danfoss set up. The five light alarm indicates over temperature in the controller which Danfoss says can be caused by high air temperature or compressor overload. Since you bench tested, would eliminate high air temp. So think either of the following: 1) Compressor low Freon or pulling high amps, or 2) Faulty controller.

Please let us know how you end up solving.

[smcboating]

Just a quick question for you cr180. My tundra fan kicks on and stays on immediately when power is provided to the unit. If I remember right under normal operation when turned on the compressor would run then the fan would kick on once enough heat was generated. Is this the case with yours?

[Richard Kollmann]

An LED trouble flashing code of 3,4, 5,6,or seven flashes every four seconds is ether an overload condition or dirty electrical current. High or low voltage or excessive fan current will not trigger a 3 or greater flash code.

Excitation of these variable speed compressor armatures to cause rotation is through electronic current pulsating three field coils. Dirty current prior to reaching Danfoss electronic control module will disrupt the 1, 2, 3 sequencing of field coils.

Excessive starting amperage during compressor start up is the typical cause of three LED flash codes, commonly caused by a high resistance in power wiring to module or contaminated refrigerant.

My recommendation to isolate this compressor starting problem by connecting a fully charged battery with a 15 amp fuse direct to module plus and minus terminals and close thermostat.

[cr180]

Originally Posted by smcboating

Just a quick question for you cr180. My tundra fan kicks on and stays on immediately when power is provided to the unit. If I remember right under normal operation when turned on the compressor would run then the fan would kick on once enough heat was generated. Is this the case with yours?

Not on the boat, but my recollection is both start together

[cr180]

On second thought, may be slight delay to fan start

[cr180]

Originally Posted by Richard Kollmann

An LED trouble flashing code of 3,4, 5,6,or seven flashes every four seconds is ether an overload condition or dirty electrical current. High or low voltage or excessive fan current will not trigger a 3 or greater flash code.

Excitation of these variable speed compressor armatures to cause rotation is through electronic current pulsating three field coils. Dirty current prior to reaching Danfoss electronic control module will disrupt the 1, 2, 3 sequencing of field coils.

Excessive starting amperage during compressor start up is the typical cause of three LED flash codes, commonly caused by a high resistance in power wiring to module or contaminated refrigerant.

My recommendation to isolate this compressor starting problem by connecting a fully charged battery with a 15 amp fuse direct to module plus and minus terminals and close thermostat.

I have experienced the poor quality DC. Ended up running a dedicated fused circuit directly from battery bypassing DC Distribution panel. Also found that unit much prefers input from AC, perhaps because other DC loads feedback into system. So have installed a high quality sine wave inverter powered by the dedicated DC circuit to provide AC input.

[Richard Kollmann]

Originally Posted by cr180

On second thought, may be slight delay to fan start

Fan stopping during compressor start up is normal on all Danfoss BD compressors.

[cr180]

Originally Posted by Richard Kollmann

An LED trouble flashing code of 3,4, 5,6,or seven flashes every four seconds is ether an overload condition or dirty electrical current. High or low voltage or excessive fan current will not trigger a 3 or greater flash code.

Excitation of these variable speed compressor armatures to cause rotation is through electronic current pulsating three field coils. Dirty current prior to reaching Danfoss electronic control module will disrupt the 1, 2, 3 sequencing of field coils.

Excessive starting amperage during compressor start up is the typical cause of three LED flash codes, commonly caused by a high resistance in power wiring to module or contaminated refrigerant.

My recommendation to isolate this compressor starting problem by connecting a fully charged battery with a 15 amp fuse direct to module plus and minus terminals and close thermostat.

Originally Posted by cr180

I have experienced the poor quality DC. Ended up running a dedicated fused circuit directly from battery bypassing DC Distribution panel. Also found that unit much prefers input from AC, perhaps because other DC loads feedback into system. So have installed a high quality sine wave inverter powered by the dedicated DC circuit to provide AC input.

But in your case, you are bench testing with household AC (should be strong and clean source) as input. The test recommended of installing battery directly to controller DC input would tell you if AC/DC converter bad.

[cr180]

By the way, if my upload worked, here is the Danfoss instructions

[Richard Kollmann]

Originally Posted by cr180

By the way, if my upload worked, here is the Danfoss instructions

\

Danfoss only provides general trouble and application information. Technicians with knowledge of these variable speed BD boot up protection circuits know voltage spikes and current disturbances (dirty supply electrical power) will prevent Danfoss variable speed compressors from restarting. Any voltmeter will detect voltage drop but not low voltage spikes due to their short duration. Each of these LED codes are designed to protect the services lift of air cooled systems and their compressor. Danfoss does not speak to these troubles because they assume power for refrigeration is adequate and comes direct undisturbed from battery. Other than a one flash LED code leave the volt meter in the tool box. An amp meter readable from miliamps to 10 amps is good for checking compressor speed setting and these small system's actual performance, as well as condition of refrigerant and condenser cooling.

[smcboating]

Thanks for your responses and efforts to help

So I have done the following:

Taken a battery out of my boat and brought it to the bench. The battery is 1 year old and on the boat it is hooked up to a pro mariner 3 bank 110v battery charger. So I feel the battery is good quality and maintained by the battery charger. I ran the battery charger last night to make sure it was topped off. The volts on the battery are reading 13v and during all my attempts to mess with it it never went below 12.7. (As a side note the Tundra AC converter that came with the fridge was providing 24v at the controller terminals.

The wires are over size with 15 amp fuse inline. Basically a 3ft run. Wires are hooked with new terminal connectors.

With the thermostat jumper in place and the fan disconnected every once and a while the compressor will turn on. Longest it’s run was 5 min other times it’s just for a second.

When the compressor runs the fridge does get cold.

I have moved the controller around and examined the circuits to see if anything is obviously loose. I have also unplugged the plug going to the compressor and reinstalled and moved those wires to the compressor around while power is applied to see if there were any type of shorts in them. None of this seems to make the compressor turn on consistently.

Still doing the 5 led flash.

[cr180]

Originally Posted by smcboating

Thanks for your responses and efforts to help

So I have done the following:

Taken a battery out of my boat and brought it to the bench. The battery is 1 year old and on the boat it is hooked up to a pro mariner 3 bank 110v battery charger. So I feel the battery is good quality and maintained by the battery charger. I ran the battery charger last night to make sure it was topped off. The volts on the battery are reading 13v and during all my attempts to mess with it it never went below 12.7. (As a side note the Tundra AC converter that came with the fridge was providing 24v at the controller terminals.

The wires are over size with 15 amp fuse inline. Basically a 3ft run. Wires are hooked with new terminal connectors.

With the thermostat jumper in place and the fan disconnected every once and a while the compressor will turn on. Longest it’s run was 5 min other times it’s just for a second.

When the compressor runs the fridge does get cold.

I have moved the controller around and examined the circuits to see if anything is obviously loose. I have also unplugged the plug going to the compressor and reinstalled and moved those wires to the compressor around while power is applied to see if there were any type of shorts in them. None of this seems to make the compressor turn on consistently.

Still doing the 5 led flash.

May still be useful to connect battery directly to controller (electronic module) to prove converter not messing up the DC input.

[OzeLouie]

Originally Posted by smcboating

Thanks for your responses and efforts to help

So I have done the following:

Taken a battery out of my boat and brought it to the bench. The battery is 1 year old and on the boat it is hooked up to a pro mariner 3 bank 110v battery charger. So I feel the battery is good quality and maintained by the battery charger. I ran the battery charger last night to make sure it was topped off. The volts on the battery are reading 13v and during all my attempts to mess with it it never went below 12.7. (As a side note the Tundra AC converter that came with the fridge was providing 24v at the controller terminals.

The wires are over size with 15 amp fuse inline. Basically a 3ft run. Wires are hooked with new terminal connectors.

With the thermostat jumper in place and the fan disconnected every once and a while the compressor will turn on. Longest it’s run was 5 min other times it’s just for a second.

When the compressor runs the fridge does get cold.

I have moved the controller around and examined the circuits to see if anything is obviously loose. I have also unplugged the plug going to the compressor and reinstalled and moved those wires to the compressor around while power is applied to see if there were any type of shorts in them. None of this seems to make the compressor turn on consistently.

Still doing the 5 led flash.

Suggest you re-read my post here #2 especially "Next, continue to monitor the voltage as the compressor starts or attempts to start." Test only with a multi-meter at the MDM + &- terminals as described. This is the industry recognised method of determining failure to start / run due to voltage drop. You could also check terminals for heat after failed run / starts as a bad connection will often get quite hot.