A) Pressurize with oxygen to 150 psig. B) Pressurize with nitrogen and trace refrigerant to 150 psig. C) Evacuate to 500 microns and wait. D) Replace the compressor immediately.
A manifold gauge cannot accurately measure the deep vacuum (typically 500 microns) needed to dehydrate a system. B. Insulated and securely clamped to the suction line. cfesa refrigeration practice test
A) Overcharged system. B) Restricted liquid line or filter-drier. C) High evaporator fan speed. D) Condenser fan running backwards. A) Pressurize with oxygen to 150 psig
High subcooling means too much liquid is backing up in the condenser. Normal subcooling is 5-12°F. D) Replace the compressor immediately
Because R-290 is highly flammable. You cannot use a standard recovery machine (must be intrinsically safe).
Refrigerant migrates to the cold crankcase during off-cycle. Upon startup, that liquid boils instantly, washing away oil (slugging). The heater prevents this.