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This work reports the observation of far infrared intermolecular vibration-rotation bands assigned to the van der Waals trimer $Ar2HCl$. A recently constructed tunable far infrared laser spectrometer was used to measure van der Waals stretching and bending transitions in the 35-45 $cm-1$ region. Both chlorine isotopes were observed and nuclear quadrupole hyperfine splittings were resolved for each vibrational transition. The observed frequencies were fit to a Watson S-reduced Hamiltonian to determine band origins and rotational constants for each state. In addition, the nuclear quadrupole hyperfine splittings were fit to determine the average angular orientation of the HCl monomer within the cluster. One of the observed bands ($\nu 0$--39.5$cm-1$) appears to be the $\Sigma $ bending $transition1$, as this state shows considerable spectroscopic similarity to the $\Sigma$ bend of ArHCl. A second band ($\nu 0$--37.2$cm-1$) evidences extensive vibrational state mixing, as the rotational constants indicate the existence of Ar-Ar stretching. This information reveals that the reversed adiabatic dynamical approximation made by Hutson, et al. in their theoretical study of three-body effects in $Ar2HCl2$ is inappropriate for the dynamics presently observed in the this system. Our results indicate the sensitivity of spectroscopic measurements to the details of the total intermolecular potential energy surface.