There are 2 vents on that regulator
A very small pin hole one on 1st stage (high pressure) and then a larger screened one on 2nd s stage (low pressure)..
Both vents allow atmospheric air in & out of non-propane side of the diaphragms that control the propane pressure.
That is primary reason for vents-----------secondary use is to let you know of a leak due to bad regulator diaphragm
Replace the regulator. Use Yellow Gas tape on threaded fittings
Cavagna makes good quality regulators.
Good time to replace the pigtail hoses (ones that go to regulator with the Big Green nut)
They are 13/14 yrs old if OEM on that 2003 Sunnybrook
