I noticed yesterday that our heat pump has a gas like smell coming from the outside vent. I don't recall this occurring before, and I'm not sure where to look. We have a Carbon Monoxide detector in the house, and that has not gone off, so I don't believe any carbon monoxide is entering the house.

Any ideas on what would cause the gas smell?

Gas smell like natural gas or propane? None of that is in your unit so it could be a neighbors lp tank or a gas grill tank.

HVAC1000,

It's not quite a natural gas smell, but it is acrid almost like nitro methane in a car engine. The smell is coming from the blower housing when the unit is running.

This is a new one on me and I am glad it is outside. You might shut the unit off and check for any burnt items etc.