Have a Jacuzzi tub in our master bath. Tub faucet has separate hot and cold water controls that mix to a single spout. Turn on the hot and you get full water pressure with plenty of hot water. But if you then turn on the cold water to mix the stream to the proper temperature, in a matter of seconds the entire flow drops significantly, almost to a trickle. When this occurs, water pressure throughout the entire house is gone. Turn off the tub faucet and water pressure immediately returns to normal throughout the house. This problem only exists with the master bath faucet. All other faucets in the house operate with full pressure at all times (except when the Jacuzzi tub is killing the pressure).
This is a new problem; it did not used to behave this way.
I assume the master tub faucet is the prime suspect in this problem? Any ideas what is happening and how to cure?
House is 12 years old. Water heater is three years old. Master bath tub and faucet is original to the house, no work has ever been done to the tub faucet.