Refrigeration Engineering

I did 3 year diploma in refrigeration and air conditioning technology and now i complete my B.tech . in my working expierence many time i saw 1 common problem in the units thats is the unit is not done cooling properly compressor work countiniously gas pressure is good but unit is not make a ice properly in ice mechine.what is it's reason.

if you need any information about air conditioning please tell me. 

According to Linde, the advantages of R600a

Zero ozone depletion potential
Very low global warming potential (~4)*
Excellent thermodynamic properties leading to high energy efficiency
Good compatibility with components
Low charges allowing smaller heat exchangers and piping dimensions

Common applications
R600a has a number of applications. It is most suited to high and
medium temperature applications. The most common applications are
for use in domestic refrigeration (refrigerators and freezers), with over
250 million units using the product. Other applications include small
display cabinets and vending machines.

You can find more info at: http://www.lindeus.com/internet.lg.lg.usa/en/images/Linde%20R600a%20Refrigerant%20Grade%20Isobutane138_11494.p