DIY - Troubleshooting LED for a BD35F

[Stingo]

My current bedtime reading is Richard Kollmann's excellent refrigeration book in which he mentions connecting a troubleshooting LED, as he does in several posts in this forum.

How do I make such an item?

[Zanshin]

It isn't difficult to do - less than a dollar in hardware. But it does depend upon which compressor you have. Which one is it? Danfoss BD-35?

[Stingo]

Yep, the BD35F

[GordMay]

See ➥ http://www.penguinfrigo.co.uk/assets...0Diagnosis.pdf

[Richard Kollmann]

Picture in my book and in my slide show both show how to connect troubleshooting LED to either a Danfoss BD35 or BD50 electronic control module. Positive side of a 12 volt LED is connected to small plus terminal along with fan red wire. Negative side of LED is connected to module D terminal.

I use a Radio Shack red LED 276-0270 because it has a 12 volt resistor built in providing correct milliamp ratting under 20 mA.


There are things you should know about refrigeration that most repair people don’t know about your Adler Barbour , Frigoboat or other type refrigeration units. This applies to Danfoss BD compressors installed after 1995.

Troubleshooting the newer Danfoss variable speed BD compressors when equipped with troubleshooting LED is easy if the following information is understood:
• LED will not signal if there is no power to Danfoss Control module.
• LED will not signal if thermostat circuit is open.
• LED will not signal if compressor is running continuously with poor or no cooling.
• LED will not signal if system is low on refrigerant, compressor will run with little or no refrigerant and still no LED signal.
• LED will flash 3 times every 4 seconds if there is too much refrigerant in system or poor condenser cooling.
• On Adler Barbour CU100 and CU200 LED will not flash when compressor stops do to a problem inside the add on stainless box. This seems to be caused by poor solder connections to fuse holder.
• If no one has tampered with refrigerant and refrigerant flow is blocked, compressor will not stop nor will LED flash on this type system. Common problem on Frigoboat keel cooler systems. Adding refrigerant will only cause additional problems.
• If there is too much refrigerant or contaminated refrigerant compressor will not start or run signaling with Three LED flashes.
• Unlike automobile computers Danfoss electronic modules micro chip only has space for one memory. Because only one memory is all that can be stored it is possible for a second problem to mask over signal covering up the first LED signal. Say the first signal is do to a low voltage giving a one LED flash every 4 seconds compressor will stop and try to restart in 20 to 40 seconds. If refrigerant pressure has not equalized in this short off cycle a restart attempt can cause a three LED flash signal indicating an overload. When a three LED flash is indicated always confirm it by turning refrigerator power off and while watching LED turn power back on. The first seen signal code is where the problem is.

If you still need help before calling a service technician Email me your questions.