That has recurred a number of times on the VolvoSpeed message board. Apparently, it is common to have the air pump suck in moisture, especially if the SAS valve starts to get sticky. the moisture collects in the bottom cylindrical portion of the plastic pump housing, and with no place to escape, it ultimately accumulates enough to burn out the motor (especially in freezing climates). the suggested fix is to drill a small (say 1/8th) hole in teh bottom opf pump housing, so any moisture will drain and never accumulate enough to interfere. Sounded good to me, so I tried it on my '95 855T. When I pulled pump, it was dry, and after i drilled two 1/8 inch holes and reinstalled, there was no change in performance or any check engine lights so apparently it doesn't change the actual pump operation. Having had to replace the '98 pump and related relay due to waterlogging, I thought trying this on the other one couldn't hurt.
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Mike Sullivan ('91 745 (171k), '93 965 (147k), '95 855T (60k), '98 V70XC (78k)