In 4th House indicates persons home, family life, ownership of the home, and vehicles, peace of mind, your childhood, teachings of your mother, grade school, and any kind of conveniences. Having an air conditioner is also considered a 4th house object since it represents convenience.
The fourth house represents the full awareness of having a home and mother, which are the next significant experience. The home environment and extensive interaction with the mother cultivate a frame of mind and the individual's emotions. The mind and emotions are, in turn, the basis for happiness. Physically, next in line is the chest, including the heart and lungs. The signification of the heart reinforces the significance of emotions. The correspondence with Karka(Cancer) adds a connection with water and bodies of water and again reinforces the signification of mind and heart.
Ketu is the south node of the Moon and the rest of the body of Rahu. This is a headless body representing separation, isolation, and the abandonment of the material world. This shadow planet represents spirituality, nothingness, and goals that we already achieved in past lives. In this life, we only rely on those things as a last resort.
The house and sign in which Ketu sits are in things we are not fond of, and we do not obsess about those things as much because subconsciously, we know we have already dealt with them. If we didn't accomplish those things in a past life, that would be seen by Ketu's bad placement as a bad sign. This will show a tug of war between both Rahu and Ketu. Ketu also searches for truth and enlightenment.
Ketu in Vedic Astrology is also an unsteady and sometimes treacherous force. Still, its qualities are more of an abstract, inward nature, in contrast to Rahu, who is more concerned with outward, worldly matters. Ketu can bring hindrance and obstacles in life's physical reality but indicate sparks of intelligence and the mind's brilliance. The above significations are extremely important to know by heart. You should memorize them and use them often to remind yourself of the essential nature of the Grahas.
Note: The degree of auspiciousness and inauspiciousness will depend upon a complete analysis of the horoscope (birth-chart).