This reminds me of the time we were having our new SX100 installed at Oregon and the Cameca engineer accidentally set the water chiller output temperature to around 60F (unfortunately it was also summer and relatively high humidity), and the cooling lines started sweating, just as you described.
Even more unfortunately, our high voltage power supply was underneath some of these cooling lines and the dripping water managed to short out the HV system completely. We had to wait a couple of weeks to get a new HV supply from France!
Probeman, knowing that you have dedicated engineer I am just wondering:
Was it HV tank or HV control board, or HV input PSU? HV tank would be very hard to damage as it is completely sealed, PSU is just converting the 220 AC into 28V DC with toroidal transformer, which should be soaked in water to short anything (and there is no water pipes above). HV control board has its main power transistors cooled by water at the bottom of the board (and it is at the bottom just in case of condensation). In case of any condensation only those transistors would be affected and it is very easy to replace and suitable replacement parts are plenty. That would had cost less time and money than to ship a new card from France to States. Sorry for the question, but just wonder how bad the condensing had to be at 15.5 C ? What normal temperature Your chillers are set? Our chillers are set to 20 C (68 F), where room temperature is about 22-23 C (71-74 F).
P.S.: I remember some funky days when I started to work on our probes, our SX 100 was temporary connected to the tap water, while chiller was on repair, and that was during cold winter and tap water temperature was 6 C (43 F), and there were no issues (maybe dry winter air at room (RH < 20%) prevented condensation). But the repair took substantially longer till summer (when tap water had about 15 C (59 F), but room humidity increased to 50% too). It is not that I would advice such a thing - currently I would rather shutdown machine completely than run it on the tap water, but for reason of T instabilities and high iron content in tap water than condensation.