Danfoss 1/4HP Compressor

[TimTech1]

Im looking at a Walk-in cooler condensing unit that has a Danfoss 1/4hp compressor. The condensing unit is outside and the crankcase heater blew. It took out the contactor and starter relay as well. I took the bad crankcase heater out of the sytem, replaced the blown components and ohmed out the compressor. The compressor at first ohmed out ok and didnt have winding to ground shorts. upon restarting the compressor drew nearly 100amps and trips breaker and wont start. I thoroughly checked everything in the condenser unit, defrost timer control, start and run capacitors, pressure controls, guages show equalized refrigerant pressure in system, I checked fuses and connections in disconnect box, the breaker in main panel passed continuity check. based on the amp draw and failure to start, I'd have to assume the compressor is bad. once when ohming the windings my meter bounced around a little before confirming continuity. Can compressors be borderline bad to the point where i dont get a definitive winding-to-winding or a winding-to-ground short? I had a Clamp-on meter on the common winding at the load-side of the contactor and a clamp-on meter on the start relay/start capacitor. The meter at the contactor got the high amps and the meter on the start circuit looked like power wasn't even making it to the start capacitor. Is it safe to assume the compressor is bad? Thanks for any feedback.

[2sac]

the crankcase heater blew

Not sure what this means, but I find it hard to believe this took out the contactor and start relay. The heater should be on the line side of the contactor and the relay on the load side. Methinks the compressor or relay was bad and one took the other out. and the cch "blew" as a fluke

[TimTech1]

Not sure what this means, but I find it hard to believe this took out the contactor and start relay. The heater should be on the line side of the contactor and the relay on the load side. Methinks the compressor or relay was bad and one took the other out. and the cch "blew" as a fluke

It doesn't necessarily matter which took out which, they were bad and i replaced them. My main question was can compressor windings be bad but yet not give a definitve open winding when ohmed out? Is it safe to assume that the compressor is bad based on failing to start and drawing high amps (after replacing and checking all the other compionents)?

[2sac]

Yes. For a unit that small, a compressor analyzer would have given you an answer in a couple minutes if the pump was bad or not.

[TimTech1]

Yes. For a unit that small, a compressor analyzer would have given you an answer in a couple minutes if the pump was bad or not.

Thanks. I appreciate your input. Ill look into getting a compressor analyzer. I've only been using a meter to check compressors.

[MicahWes]

Are you sure a walk-in has only a 1/4 hp compressor?

[oyader]

Did you only check continuity? What did each leg ohm out at? 1/4hp seems small for a walk in, 100 LRA seems high for a 1/4hp anything.

[TimTech1]

Did you only check continuity? What did each leg ohm out at? 1/4hp seems small for a walk in, 100 LRA seems high for a 1/4hp anything.

The Common to Start winding was 2.1 ohms, the common to Run was .7 ohms. Run to Common was 2.8,2.9..The Run winding bounced around some each time I ohmed it out. The rated RLA was 24Amps. I cant remember what the rated Locked Rotor Amperage was, maybe 80something.. Its a 404A system.