I just did a single pole installation with a PR180. It turns a light and fan on in my bathroom. The wiring appeard simple black to hot, red to load, yellow/red not used, green to ground. The fan and light work great in the on position but in auto they are getting half the normal voltage. Is this a problem with the switch or my wiring?

Hm, your wiring description does not seem to match the web description.

http://www.aartech.ca/docs/PR180-1LW-SPEC.pdf

The "Source (IN) to the switch is connected to Black.

The "Supply" (Out) of the switch is yellow. This feeds the Black lead on the load (in this case the light).

Red is capped off. Ground (green) is connected to the bare ground lead.

White is the Return (Neutral) from the load and is not routed through the switch at all.

The pdf is different but only the colors I still have it wired the same as the diagram on the pdf, any ideas?