Air conditioning problems

[mallen88]

In my 2006 Sentra the air conditioning blows nice and cold and then for a couple of seconds it blows warm. It only blows warm for a few seconds but it's enough to notice and then goes back to blowing cold. This problem is repeated while the air is on. The dealer told me that this was normal operation. I don't think that is true because it just started happening this week. Has anyone had this problem? I don't know if it's the blend door or the high pressure switch. Any ideas would be great. Also, I put my thermometer in the middle vent and drove around. The air conditioning was blowing at 33 degrees and it would go up to 47-48 degrees real quick and then back down.