Time to check out the circuit
diagram!
Take a look at the line from J16 on the main control board (AJUNC-3) to the drying pump. I see a solid-state relay (I also notice there is a fuse before the pump, BTW)!
I would say that "hearing the air valve" (43) is a Red Herring; the diagram shows it coming off JP12 (that is, not connected to the drying pump).
I tried the air pump by otself applying voltage directly and it works fine.
Try farther back - at the sold-state relay. Is it working?
On the other hand, I see that Juan is saying that the "In-Out test" won't run - which sounds a bit odd. Maybe he needs to confirm that (and if that is indeed the case, consider a system reset, fitting a new NVRAM, or whatever). Final thought - and it may sound like a daft question - but I suppose that the "UP" button is working OK?