The W124 and W126 CCU's don't have any sort of "overload protection" built into them. If the pump seizes (I've dealt with 3 of them now), they burn out a transistor on the board. Problem solved.

Since the OP was working in the cluster area, check the main plug on the key switch. There is a dedicated circuit off the main switch for the fan motor. It's possible the wiring got disturbed or disconnected somehow. Otherwise, it's likely coincidental.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)