With reference to main refrigeration plants give reason for each of the following operational irregularities and state how these are dealt with:

(a) Rapid loss of lubricating oil from the crankcase of a "Vee" block compressor (4)

(b) Steady "fail off" in refrigeration effect over a comparatively short period of time (4)

(c) Excessive "icing up" at compressor suction (4)

(d) Short cycling (4)