The answer to 'pressure regulator frozen' is that a frozen pressure regulator is a common plumbing issue, typically caused by cold temperatures or a buildup of mineral deposits. Symptoms include low water pressure, strange noises from the regulator, and the regulator becoming stuck in place. The solution is to thaw the regulator and clean or replace it if necessary.
If the regulator is frozen, you can try to thaw it by wrapping it in a heating pad or towel soaked in hot water. However, if the regulator is severely damaged or the issue persists, it's best to call a professional plumber to properly diagnose and fix the problem.