It's a fact. When the aux pump begins to develop leaky seals, the motor shorts and draws a ton of current. On the '87 there's an automatic circuit breaker. If the pump is unplugged, everything else will start to work. Earlier cars had fuses inconveniently located on the backside of the head unit, This is from the FSM:

"The circuit board in the tempmatic pushbutton control
unit is protected against shorts from any of its externally
connected circuits. The respective output
signal, i.e. blower and A/C compressor, is switched
off, and the blend air flap remains in its present position.
The respective output signals are switched on
again after the short-circuit has been eliminated.
Due to this modification, the two ampere fuse in the
tempmatic pushbutton control unit is no longer required."