A.admit only enough fresh outside air to provide proper ventilation
B.reduce the air reheating system load
C.lower the compressor head pressure
D.operate the purge recovery unit continuously

A.lowest absolute humidity
B.lowest relative humidity
C.highest absolute humidity
D.highest relative humidity

A.change from blue to orange
B.‘flare up’ and remain lighted
C.probably go out
D.stay blue

A.flushed with clean refrigerant oil
B.purged with the refrigerant
C.washed with an ammonia and alcohol solution
D.grounded to compressor

A.petroleum crystals
B.phosgene gas
C.water vapor
D.carbon monoxide

A.be clear
B.be blue
C.be light green
D.show bubbles