Expensive Refrigeration Design Error

[Richard Kollmann]

From several emails and comments on Rparts web forum there is a strong indication that Danfoss BD80 compressors are possibly failing do to oil starvation caused by oil pooling in oversized holding plate coils. To prevent compressor oil starvation lines must be small enough in diameter to keep refrigerant velocities up. It seems that there is no way to predict how long it will take before these compressor locks up; one system ran for two years another one year. One system had a Grunert holding plate designed for a larger compressor having a ½ inch return line. The first indication of a problem was a compressor overload LED signal of three or four flashes. If someone has found a solution to this problem short of replacing holding plates I would like to hear from you.


There are other reasons why a Danfoss BD compressor will indicate a 3 LED flash overload signal:

• The most common cause of an overload is I a newly assembled system caused by a plugged line at a solder connection.
• Too much refrigerant or poor condenser cooling indicated by compressor running for a short time at high amperage.
• Blocked expansion device common on expansion valves when inlet screen is plugged or when temperature sense tube is damaged. Blockage of capillary tube expansion devices is not common on system where it is protected by properly installed filter/dryer.

There is a test for a BD compressor lock up caused by oil starvation if a system has both a high and low pressure refrigerant service connection by using a servicing gauge set to by passing the rest of the refrigeration system. Currently all of these suspected compressor lock ups seem to be occurring on Rparts Kits 2 that incorporates a large receiver with a King valve where high pressure servicing gauge can be connected


One way to bypass system to see if compressor will run with no load:


1. Remove the center Yellow hose from Gauge Set.
2. Place one of the standard servicing caps on center gauge port.
3. Purge gauge set and hoses with fresh refrigerant.
4. Connect both high and low pressure hoses and both gauges will read pressure in system.
5. When both hand gauge valves are open refrigerant will not leak out because center gauge port intended for refrigerant hose is capped.
6. Open both gauge valves open power up compressor. If compressor does not run and LED still flashes 3 or 4 times compressor is seized.

[James S]

I'm hoping is that when I bought my "system" all the pieces were sized to work together...I've tried it to see that it works...but haven’t run it more than 24hrs since I'm still refitting.