There are reports of individuals having experiences with "Phantom smells" in some locations that are suspected to be haunted. These can be residual related in that they are somehow imprinted in the fabric of the environment just as some hauntings are. They themselves can be an aspect of a haunting or can be the haunting itself. These are olfactory anomalies that we can pick up on and at times there is no root cause of where these smells are emanating from. There is the possibility that there are certain smells within the environment that are permeated there over time. In older homes this is common. There could be smells of fireplace or cigar smoke or in and around a kitchen there could be smells of food. During summer it can be much warmer and these scents and smells can be much more noticeable. They can be trapped in the wood work or even the walls.I would, though ,do all you can to see if there is not another logical explanation for what could be causing these phantom smells, the explanation could be right under your nose. Take care.