DANFOSS BD35F fridge.

[xamtex]

hi,not sure if this is the right place to post this.but...
i recharged the system on a mazda bongo camper today(no problems)and the owner asked me to have a look at his fridge..its a vitrifrigo C42L with a danfoss BD35F compressor.
i recharged it with the correct amount of R134a but its still doing the same as before.....
compressor starts up(condensor fan starts too)runs for about 5 seconds then the compressor stops...fan keeps running for a while then stops.....then the compressor restarts(with the fan as before)runs for 5 seconds then stops....keeps cycling like this...no cooling?
any ideas?

[monkey spanners]

Is this one of those 12volt comps?
What is turning in on and off?

[xamtex]

yes,its a 12volt fridge...im not sure whats turning it on and off..
on startup i have 4.5 volts to the stat...and 4.5volts back to the controller...when the compressor stops i have 0 volts to the stat...so it seems the controller is stopping it....but why?

[Chef]

.im not sure whats turning it on and off..
?

xamtex
Here is the circuit diagram for the unit and it shows how to connect an LED - it is an option, After that the fault code can be seen flashing on the LED and should give you a clue as to what is happening. My guess is it is overloaded either by too much charge or the RPM is set too high? Low voltage on the 12v system does not repeat start but just does not start.

Chef

[nike123]

Troubleshooting 12 volt Danfoss BD compressors.
There are two different series of Danfoss BD 12 volt compressors the older fixed speed and the newer variable speed . If the refrigeration unit is over 10 years old and has a Danfoss BD 2 or BD2.5 or BD3 compressor then it has the older fixed speed discontinued electronic 4 pin module. Troubleshooting Danfoss compressors with 4 pin modules consists of the following steps:

1. All of these compressors have a 4 pin module connector and their modules contain a replaceable fuse. If this fuse is blown there are two reasons why either power wires to module are reversed or module has an internal failure.

2. Check to see that there is actually power at the refrigerator control module.

3. Place jumper wire across thermostat terminals on electronic module, Compressor still does not run go to next step.

4. Disconnect black fan wire from electronic module, Compressor runs, replace fan. Compressor still does not run after fan ground wire is disconnected, go to next step.

5. Run correct size and correct polarity jumper wires direct from a fully charged battery in order to bypass all boat’s wiring. Volt meter readings are of no value when looking for voltage spikes. Compressor still does not run electronic module needs to be removed and tested on another unit. If there are no other units available to test your module on I will test all 12 volt Danfoss control modules free except for BD80 compressor modules. Email me for shipping address and details. richard@kollmann-marine.com

Small 12/24 volt boat refrigeration units using Danfoss BD compressors manufactured after 1996 will have a BD 35 or BD 50 variable speed compressor with a troubleshooting computer chip built into control module. This circuit makes them easier to find troubled area if compressor fails to run. If this unit does not have this $2 LED install one. Without the LED on these new units troubleshooting will be the same as earlier 4 pin Danfoss BD compressors.

Trouble shooting LED will only flash if electronic module sees a compressor problem. In each case problems of compressor’s failures to run are identified by counting number of flashes of LED:
• No LED flashes would indicate either thermostat is open or no power to module.
• One LED flash and a 4 second pause indicates a non Danfoss wiring electrical resistance problem or low batteries. Because of module’s sensitiveity to milliseconds of a voltage spike they cannot be detected by a voltmeter. Solution is to bypass power wiring till resistance problem is located.
• Two LED flashes indicates fan over current cutout. If fan circuit on these variable speed compressors exceeds 1 amp compressor start up will be aborted. This condition can be confirmed by disconnecting Black fan wire at module, if compressor runs replace fan.
• Three LED flashes indicate excessive torque is required to start compressor. This is commonly caused by turning compressor off and back on too quickly or too much refrigerant or poor condenser cooling. Most people jump to the conclusion that there is a mechanical rotor lock up inside compressor and this is a mistake on Danfoss BD compressors.
• Four LED flashes indicate compressor motor not reaching sustained controlling speed above 1,850 rpm quick enough.

If someone has tampered with refrigerant by connecting gauges to a system letting air in or adding too much refrigerant can cause either a Three or Four LED flashing signal. On water cooled Danfoss condenser systems three and four LED signals are common when seawater gets into refrigerant circuit.

..........................

[lawrence1]

xamtex,
Your battery needs to be checked first,,,these compressors hate low voltage,,,if the battery is a little low the compressor will trip out,,check for tight terminals as well.

[Chef]

xamtex,
Your battery needs to be checked first,,,these compressors hate low voltage,,,if the battery is a little low the compressor will trip out,,check for tight terminals as well.

lawrence - your quite right that these systems are very voltage sensitive but it may be adjusted and the factory could have installed a specific resistor to get the unit to run as low as 9.6V DC. See the table.

Even so the OP said the compressor ran for 5 seconds and then turned off and then cycled this way. If it is low voltage the unit will simply not turn on, not at all, so it cannot really be low voltage but always worth checking connections.

[xamtex]

thanks for the replies...i will get an led next week and run a selftest,see if that comes up with the answer.

[ryanzhao]

4.5 v of course is not good. and what amp ?

[heallen]

How much gas did you put in the unit?

[xamtex]

label said 78 grams i think?

[RobertvK]

Hello There,

Might be an off subject. I have a broken refrigerator control unit BD50F (danfoss) on my sailing vessel, and currently we are out of reach of any suitable repair shops. We want to connect directly to the motor connection with 12V for the time being.
Anyone knows the wiring diagram or function of the three connection points on the motor. (between control unit and the motor unit). Probably two of those need to be connected to the + and one to the -.....

Many thanks,

Robert

[monkey spanners]

Hello There,

Might be an off subject. I have a broken refrigerator control unit BD50F (danfoss) on my sailing vessel, and currently we are out of reach of any suitable repair shops. We want to connect directly to the motor connection with 12V for the time being.
Anyone knows the wiring diagram or function of the three connection points on the motor. (between control unit and the motor unit). Probably two of those need to be connected to the + and one to the -.....

Many thanks,

Robert

Hi Robert,

I think the compressor needs the module to drive it, is more complicated than just a box with a relay in and i suspect you risk damaging the compressor too by running it directly.

Jon

[lawrence1]

RobertvK,
Don't try it.

[nike123]

It cannot be run directly.

Danfoss BD brushless compressors do not have a DC 12 volt motor inside compressor so connecting any power source other than a Danfoss module can destroy compressor. The Danfoss BD 50 model compressors are connected to only modules having connector plug. These compressors run at a fixed speed and are controlled by reversing low voltage current produced from the electronic module. There are two large field coils inside the fixed speed compressors to excite the solid metal compressor armature. Armature rotates when module reverses polarity of magnetic fields at 2000-3500times per minute (depending on selected speed by control resistor). Not only does the module cause compressor to run it also protects compressor from high amperage, low voltage, and high fan circuit loads.

[brusok]

I have a Danfoss BD35F unit . I have no acess to a 1010n0220 controller to trouble shoot with. To test only the motor , what resistance should I measure between the 3 current input pins on the compressor ??
Brusok

[nike123]

http://www.danfoss.com/BusinessAreas...c70afddfd.html