I think you changed the Piston type compressor, you need a rotary type. which takes less load.
Alteration is just ********, duet compressor is another ****, mechanics here are full of ****. So I strongly suggest u all to buy 1300cc car with its original ac or otherwise use Honda 125 in summers.
self edit
old thread......
Today i changed my cuore stocked Compressor with kabali compressor due to cooling issue....after changed of compressor i feel very less load on engine...pick of car also enhanced...AC result is very gd now even in 44 degree temp it cools the car very gd....total cost with labour was 12000/- Rs 7000 compressor....9000 dryer...general services of cooling coil...blower fan...condensor....and Gas filling Rs4000...
Duet compressor is heavy fo cuore, engine will make problems later.Mini pajero ac compressor is not so powerful to chill cooling in cuore.Both above are not recommended.Buy new compressor of cuore will help u.