There is some relationship between the pump and the monovalve. It has to do with the CCU in some fashion.

When the pump draws too much current, the CCU does some funny things with the monovalve.

I had replaced the pump with an aftermarket unit, and, within six months, the monovalve started making quite a racket........very loud cycling. Disconnect the pump and the monovalve returns to it's normal function.

What's going on inside the CCU is certainly a mystery.