Author Topic: No Start Problem on Danfoss 4 pin BD 2, BD2.5, and BD3 Fixed Speed Compressors  (Read 1147 times)


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The boot up test circuit in module works much the same as in booting up a computer. During the module boot up sequence it checks starting amperage peak, Voltage spikes high and low it also tests fan cooling amperage. When there is a fault detected in this electronic module protection circuit you will hear a beep as power transistor switch opens power circuit in module preventing compressor from starting. Fan will always start and stop running during compressor normal and false start attempts. 

A compressor identifying an electrical problem will try to start compressor every 30 to 60 seconds until problem is corrected. If you followed my troubleshooting steps correctly; Disconnected black fan wire, eliminated all boat wiring by powering module with positive and negative jumper wires direct to a fully charged battery then and only then would  the electronic module be questioned. Conditions like no Compressor start up are normally caused by a weak circuit breaker, Old boat wiring or any corroded wire connection. Be sure to also check fuse holder contacts in module for signs of dirty overheated condition.