Boost kits....

some are installed by the factory. Scroll compressors typically dont need them where as recip compressors needed them when a txv was in the circuit.

What's the diff between scroll and recip. compressor??
Thanx for the help...

They cost quite a few dollaros $$ so they don't put them on anymore but have them as a add on option. If the unit is to be used in low ambient temp conditions around 50 deg F (usually in a commercial app) then the oil is thicker and one may be required.