Wash Your Pack !
Summer is the best time to wash your pack because they dry fast and you won't get mildew. Fill a tub with water - cold is fine - not hot - especially with dyneema or spectra since the coating adhesion can be weakened. A mild dish soap is fine to use but nothing stronger. Amonia will remove waterproof coating - other chemicals may also, so keep things simple. Mostly, you want to loosen the dirt and SALT. Salt buildup can hurt the frame inside the frame tubes mostly at the base where fluids accumulate and dry. Salt also attracts animals that want to eat the salt and then your pack! Scrub with a nylon bristle brush. Do not scrub the inside coating unless you are trying to remove the coating!
Do not remove the frame since the pack will shrink when it drys and you won't get the frame back in. It may not be a bad idea to wash the pack once in a while while on a long trip like the PCT. Do it on a rest day - the packs dry fast and it may save you rodent damage later down the trail. Rodents can destroy shoulder pads and hip belts, especially at night while you sleep.