  We investigate the influence of convective overshoot on stellar evolution
models of the thermal pulse AGB phase with M_ZAMS = 3 Msol. An exponential
diffusive overshoot algorithm is applied to all convective boundaries during
all evolutionary stages. We demonstrate that overshooting at the bottom of the
pulse-driven convective zone, which forms in the intershell during the He-shell
flash, leads to more efficient third dredge-up. Some overshoot at the bottom of
the convective envelope removes the He-H discontinuity, which would otherwise
prohibit the occurrence of the third dredge-up for this stellar mass. However,
no correlation between the amount of envelope overshoot and the efficiency of
the third dredge-up has been found. Increasingly efficient third dredge-up
eventually leads to a carbon star model. Due to the partial mixing efficiency
in the overshoot region a C13-pocket can form after the third dredge-up event
which may be crucial for n-capture nucleosynthesis.
