Working on a 2000 Ford Expedition 5.4L, having trouble with the pressure relief valve relieving itself even at low refrigerant levels. Checked the orifice tube and it was not clogged, but did have very few metal fragments which could mean that I'm low on PAG oil with all these pressure releases. Decided to get a new pressure relief valve and also decided to go with a variable orifice valve tube this time instead of the standard replacement orifice tube. And, while I'm in the process, decided to change the clutch pressure switch. The clutch pressure switch is located on top of the accumulator/dryer and you have to take a couple of bolts that hold a bracket off and slide that bracket forward to be able to get to the clutch pressure switch. The orifice tube was way easier to get to by taking the plastic fender well off. Easy access to the orifice tube location and also the pressure relief valve on the manifold block mounted to the back of the AC compressor.