You CAN change the compressor by releasing ONLY the valve block to compressor fitting. Another alternative to those not wanting to do the SDD route is to get a Foxwell scanner (there are others as well) loaded with proprietary JLR software that does many SDD functions in a handheld unit. Mine was about $150.00 and has a full compliment of suspension functions, such as initialize, release pressure, calibrate, etc. It also does many others, such as the elusive oil change reset, which there is NO other way to do,