In my experience...

the heart chakra is like the engine of the soul (i.e. the self)

the mind is the steering mechanism of the heart

the heart is philosophically and scientifically -approximately- one part fire and one part water

hemoglobin red blood cells for example carries oxygen through the body. Oxygen is the sixth element and is responsible for the majority of combustion and corrosion on earth. As such breathing is actually considered cellular combustion.

Philosophically and anatomically the heart is the center of the self. It is best represented as desire/emotion. the properties of desire is... 'A consuming force that is never satisfied'... which is -philosophically- the same definition as fire (actually what we consider fire is mostly just heat).

Additionally, the "fire" is a life giving force that makes "alive"... that is, 'too quicken' or a feeling of "exuberance" or "mania" hence the water aspect, as the life giving force.

Tears are a physical manifestation of the yin feminine water principle for example.

additionally...

the two most common... "problematic" chakras are the Vishuddi (throat) and the stomach chakra (located at the belly button -seems to be a lot of confusion about this chakra*-) (stomach/ digestion) these two chakras are situated on opposite sides of the heart and cause the most damage/hinderance to spiritual development because they... "block" energy channels of the two higher (ajna and sahasrara) and lower chakras (muladhara and saccral)