delta shower valve body - no water

[jrburt]

I have a 1995ish Delta single handle shower valve (model 1300 or 1400 scald guard I think) and I'm only getting a tiny trickle of water out of the shower head. I have replaced the cartridge but no change. I have both hot and cold water when the cartridge is removed. I removed the shower head and cartridge and tried to blow with my mouth from the shower head end of the pipe and didn't get any air flow. I tried to blow through with an air compressor and air wouldn't go through. The only thing there is the valve body. Show air flow freely through the valve body? Any thoughts?