  Radiative cooling and AGN heating are thought to form a feedback loop that
regulates the evolution of low redshift cool-core galaxy clusters. Numerical
simulations suggest that formation of multiphase gas in the cluster core
imposes a floor on the ratio of cooling time ($t_{\rm cool}$) to free-fall time
($t_{\rm ff}$) at $\min ( t_{\rm cool} / t_{\rm ff} ) \approx 10$. Observations
of galaxy clusters show evidence for such a floor, and usually the cluster
cores with $\min ( t_{\rm cool} / t_{\rm ff} ) \lesssim 30$ contain abundant
multiphase gas. However, there are important outliers. One of them is Abell
2029, a massive galaxy cluster ($M_{200} \gtrsim 10^{15}$ M$_\odot$) with
$\min( t_{\rm cool}/t_{\rm ff}) \sim 20$, but little apparent multiphase gas.
In this paper, we present high resolution 3D hydrodynamic AMR simulations of a
cluster similar to A2029 and study how it evolves over a period of 1-2 Gyr.
Those simulations suggest that Abell 2029 self-regulates without producing
multiphase gas because the mass of its central black hole ($\sim 5\times
10^{10} \, M_\odot$) is great enough for Bondi accretion of hot ambient gas to
produce enough feedback energy to compensate for radiative cooling.
