单项选择题
A.high discharge pressure B.frosting of the crankcase C.high temperature of the overboard water D.low suction pressure of compressor
Air that may enter a refrigeration plant tends to colle...
单项选择题Air that may enter a refrigeration plant tends to collect in the （）.
A.upper part of the receiver B.upper part of the condenser C.down stream end of the cooling coil D.outlet end of the condenser
Moisture should be kept out of an R-12 system because i...
单项选择题Moisture should be kept out of an R-12 system because it tends to cause （）.
A.icing of the automatic controls B.embrittlement of some parts of the automatic controls C.sludge in the lubricating oil D.all of the above
Black smoke coming from a boiler can be caused by （）.A....
单项选择题Black smoke coming from a boiler can be caused by （）.
A.low water level B.high water level C.excessively high fuel pressure D.low oil temperature
