  For central collisions of $^{40}$Ca $+ ^{40}$Ca at 35 MeV/nucleon, the
density and temperature of a fragmenting source have been evaluated in a
self-consistent manner using the ratio of the symmetry energy coefficient
relative to the temperature, $a_{sym}/T$, extracted from the yields of primary
isotopes produced in antisymmetrized molecular dynamics (AMD) simulations. The
$a_{sym}/T$ values are extracted from all isotope yields using an improved
method based on the Modified Fisher Model (MFM). The values of $a_{sym}/T$
obtained, using different interactions with different density dependencies of
the symmetry energy term, are correlated with the values of the symmetry
energies at the density of fragment formation. Using this correlation, the
fragment formation density is found to be $\rho/\rho_0 = 0.67 \pm 0.02$. Using
the input symmetry energy value for each interaction temperature values are
extracted as a function of isotope mass $A$. The extracted temperature values
are compared with those evaluated from the fluctuation thermometer with a
radial flow correction.
