My PA30 electric trim will not activate nose up trim with the yoke mounted switch. When the Auto Pilot is engaged trim works normal in both directions, up and down. When activated with the yoke mounted switch, the trim moves nose down but not nose up. When switching between nose down and up you can hear a click in the back of the plane near the servo, but no movement. Any suggestions on what to tell my mechanic to look for?

I would start by checking the microswitches in the yoke.

Thanks, Kristin.
That was my first thought and in a preliminary check, they appeared to be ok.
All wiring was intact and since it does make one click in the back when activated from down to up we thought it may be an issue in the back of the plane vs. the yoke switches. The yoke switch has had issues in the past... several years ago.