In regards to R22 alternatives retrofits including; Danfoss, Tecumseh, Trane 3D and Copeland – scrolls don’t incorporate an active oil pump in them.
The lack of lubrication can be caused by a couple of different ways:
1. When oil is going out the discharge side and the suction gas doesn’t mix with it, it won’t come back to the crankcase.
2. If oil and liquid refrigerant are in the crankcase together, the refrigerant is heavier than the oil and will sink to the bottom and won’t lube the lower bearing which in turn won’t lube the upper end either.
MO-99 specifically mentions the Trane 3-D and Danfoss SM in their literature. They recommend adding POE oil. Trane in their own bulletin says to add 12 oz. of POE on a scroll compressor.
According to a Copeland guide, “scroll compressors have no positive displacement oil pump and therefore no oil pressure switch.”
“An oil change to POE is recommended for systems designed to lubricate compressor bearings by pulling oil from the bottom on the oil sump, such as with Danfoss SM scroll and Trane 3D compressors.”
In an effort to reduce confusion as well as the risk of compressor failure, attached are several documents for reviewing.
*Information provided by Kevin Morris – Charles D. Jones Company Refrigeration Product Specialist