Before washing you may want to place handfuls of the fleece into a "fine washable net, zippered bag". The large bag holds about 1/4 of a pound of wool and will keep it in it's lock formation while soaking. You can use your washing machine, BUT ONLY AS A CONTAINER. NEVER use the agitation cycle when wool is in the washer. Always fill the washer with the very hottest water and set hot water heater to 140 degrees if possible and add detergent. You can use most any sort of laundry soap or dishwashing liquid. Some like to use Orvus, a livestock animal washing paste from the livestock supply store. Turn the washer completely off and gently press in the bags of wool without doing any agitation, sloshing, etc. You can use the spin cycle for removing the water, but remove the wool before refilling the washer for the rinsing soaks. Fleeces with a very high grease/lanolin content may need 2/3 cup of Arm and Hammer super wash added to the first wash. Combine the soap, hot water, super wash and mix well.
Never let the soaking water cool down, as the lanolin resets into the wool.
It's OK to use the spin cycle of your washing machine to remove the water in the tub. The wool is moving in mass around the agitator...and not being agitated, just moving all at once while the water drains out.
After spinning the excess water out of the wool, remove the bags and refill the machine with hot water for the soaking rinse. When washing wool that isn't very dirty, do only 1 soap soak and 2 clean water soaks. In the final soaking rinse of thw wool, the water should be clean and the wet wool should no longer smell like lanolin. If it still smells like lanolin, months later the wool will become sticky and gummy and may pill when carding.
After the final spin cycle, remove the wool fromt he zippered bags and spread out on a table on a towel or a screen so the wool can dry. Pull the wool apart after several hours for better drying. It should take one to two days depending on the time of year.