I am having a problem with my air conditioning system in my Nissan Pathfinder. The system has worked fine up until a few weeks ago. I noticed that it was not getting any cold air, and the A/C button on the dash would not come on. I inspected and replaced a spade fuse, but that was not the problem. Then I noticed that when the blower is set to "1", the A/C light will come on and there is a light breeze of cold air at the vents. If I switch the blower to any other speed, the A/C light goes out and I just get ambient temp air through the vents. Then, out of nowhere today, I had the A/C on and the blower set to "1". I just happened to flip the blower to "4" and the A/C light stayed on and I got cold A/C. It stayed on for about 30 minutes, and worked as cold as it ever had. My Pathfinder actually got too cold, so I tried setting it to "3", and it then stopped working and the A/C light went out. Any idea what is causing this?