I soldered the one handle type shower regulator in place. Turning the handle full hot, have plenty of flow. But the cold side is just a trickle. I do not see any adjustments on the regulator. Other cold water lines on the same path are fine. Bad regulator?

Thanks

Sounds like you might have dislodged some crud built up in the pipe wall and now it's clogging the cold water inlet port of the cartridge. Shut the water off and open up the valve. Check and clean the inlet ports in the cartridge. Before you button things back up turn the cold water on for a minute to flush out the supply line. Reassemble and try it now. Or perhaps the screwdriver stop on the cold side of the valve's closed.
Good luck, Tom

I soldered the one handle type shower regulator in place. Turning the handle full hot, have plenty of flow. But the cold side is just a trickle. I do not see any adjustments on the regulator. Other cold water lines on the same path are fine. Bad regulator??

Thanks
Thanks Speedball for the quick response. Will checkout your ideas.