  We present follow-up observations with the Sunyaev-Zel'dovich Array (SZA) of
optically-confirmed galaxy clusters found in the equatorial survey region of
the Atacama Cosmology Telescope (ACT): ACT-CL J0022-0036, ACT-CL J2051+0057,
and ACT-CL J2337+0016. ACT-CL J0022-0036 is a newly-discovered, massive (10^15
Msun), high-redshift (z=0.81) cluster revealed by ACT through the
Sunyaev-Zel'dovich effect (SZE). Deep, targeted observations with the SZA allow
us to probe a broader range of cluster spatial scales, better disentangle
cluster decrements from radio point source emission, and derive more robust
integrated SZE flux and mass estimates than we can with ACT data alone. For the
two clusters we detect with the SZA we compute integrated SZE signal and derive
masses from the SZA data only. ACT-CL J2337+0016, also known as Abell 2631, has
archival Chandra data that allow an additional X-ray-based mass estimate.
Optical richness is also used to estimate cluster masses and shows good
agreement with the SZE and X-ray-based estimates. Based on the point sources
detected by the SZA in these three cluster fields and an extrapolation to ACT's
frequency, we estimate that point sources could be contaminating the SZE
decrement at the <= 20% level for some fraction of clusters.
