Scroll Compressor failures

Some obseravtions regarding Scroll compressors:-

1.They were provided to replace the reciprocating Bristol compressors which had high failure rates.
2.Even scroll compressors in 2003-04 LHB coaches are having FRPCPY of over 20.
3.Howrah division has pretty less FRPCPY since their coaches are new.
4.Coaches of 07 and 08 series have had less failures in Mumbai Divsion.
5.Scroll compressors when fitted in SGAC coaches are found to work well.
6.None of the scroll lasts the life of 8 years. They fail in first three years of years.
7.Failures are comparitevy less reported in NR and ER.

Now the question is why they fail so much :-
Some contributing factors are:-
1.Bypassing of LP switches in order to "push" cooling.
2.Choking in the 'solenoid' which is redundant in the system.
3.Bypassing of sensors after failing of sensors.
4.Choking of Dryer.
5.Leakage of oil from capillary, and no provision of top up.
6.Overcharging of gas (it requires not > 3kg for LEEL and 3.5 kg for Sidwal RMPUs)