Pressure in the filter, flow of water not good

In some models it creates an automatic by-pass when the filter is removed. If this is one of those models remove the filter and use the dispenser with it out. If you get good pressure now, it indicates a problem in the filter housing. If it's still slow it could be due to low supply water pressure or a defective valve. You can check the water at the valve inlet and outlet. First turn the inlet (main) water supply valve off. Now disconnect the water inlet line at the valve and place the end of it in a pitcher. Turn the water valve back on and check if there is a good solid water flow. If the water flow is good reconnect the water to the valve and now take the water line loose on the back side of the valve. Activate the water dispenser and check how the water flow is coming out of the valve. You will probably need another person to help you with this check. If the water seems slow, then the valve will need to be replaced.