I bought desert Cooler from Ram cooler 4 years back. The cooler comes with only 1 year warranty. For the last 4 seasons, I have not come across any problem with this cooler. I only got it serviced once after 3 years for change of wood wool. The cooler has big cooling pads and works very effectively during the dry summers. As the rainy season start, the humidity rises and the effectiveness of cooler decreases.
I highly recommend the Nagpur coolers to everyone for real cooling performance.