I have a peerless single valve faucet in my stand up shower stall. When disassembled I get great water pressure. When I assemble the faucet back on and turn the water on I can't get the water to go to the shower pipe... to the shower head. I looked in the unit and can't seem to find anything blocking it but did try to blow compressed air into the shower head pipe and it doesn't allow air to escape from the disassembled valve below. Any suggestions? Do I have to purchase a new valve or can I fix this one?

Have you remover the shower head and turned then water back on to see if water came out of the open pipe? Your diverter is on the spout isn't it? Let me know, Tom