  We describe initial results of a search for redshifted molecular absorption
toward four millimetre-loud, optically faint quasars. A wide frequency
bandwidth of up to 23 GHz per quasar was scanned using the Swedish-ESO
Sub-millimetre Telescope at La Silla. Using a search list of commonly detected
molecules, we obtained nearly complete redshift coverage up to z_abs=5. The
sensitivity of our data is adequate to have revealed absorption systems with
characteristics similar to those seen in the four known redshifted
millimetre-band absorption systems, but none were found. Our frequency-scan
technique nevertheless demonstrates the value of wide-band correlator
instruments for searches such as these. We suggest that a somewhat larger
sample of similar observations should lead to the discovery of new
millimetre-band absorption systems.
