Why is my high pressure side of AC high in 2004 jeep Cherokee?

Well, it could be for a number of reasons. AC systems have seven "conditions" which they operate in, and more than one of those conditions results in excess pressure readings on the high pressure side. If you had the low pressure side readings and ambient air temperature available, it would be easier to narrow it down. Also, when you took the readings, did you set a fan approx one foot in front of the grill, and have it blow air into the grill? If not, it's possibly you got a false reading.