well, the truth is: (ture story, 14th april 2006) 
I went to repair the AC of my newly brought Nissan Sunny 98, engine was not so good at that time, diesel was nearing the end point. car was standing on slop in AC workshop, fuel pump sucked some 'kachra' and thrown it towards engine.
After that ...
engine failed to start, and about 4-diesel mechanic took about 2-days to diagnose the problem, and yesterday about 4:pm, the bad news,,,, 'engine was expired ' may allah keep it with angles
.
then...........
Mechanic trade-off this engine with 'kaaabli' 2.0D 2000model nissan engine within 14000 rupees only.
i was happy to see that i will be having new engine for this much amount.
ppl say that this engine will work fine for about 2 to 3 years, if proper care/mainiaining is provided.
what a way to close the journey towards repairing AC 
anyhow if it gives performance, i will forget this amount, and will enjoy it's drive. 
thanx to all of you to keep this post alive, and for proivding ur experienced info.