Diagnosis
Rapid, loud bubbling or a 'hard boil' sound is normal during the initial heating phase. This is water boiling vigorously before enough steam is generated to close the float valve and begin pressurization.
How to Fix It
No fix required. 1. The sound will diminish once the float valve pops up. 2. The display will change from 'On' to the pressure count-up timer. 3. This process typically takes 5-15 minutes depending on contents and quantity.
If That Didn't Work
If the loud boiling sound persists for over 20 minutes and the float valve never rises, you likely have insufficient liquid. Cancel, cool, and add at least 1 cup of water or broth.
Heads Up
This is distinct from a high-pitched hissing or whistling, which indicates the steam release handle is not fully sealed in the 'Sealing' position. Ensure the valve is turned fully to the left.