2005 Prius w/ a little more than 97K on the odometer. The other day I went to go somewhere and turned on the AC and set it to Max Cold setting. My problem is the cabin fan keeps changing it's speed very erratically. Instead of going to full speed (like it should when set to "Max Cold" but instead will mostly turn on what I would call very slow. I know it is running because even when standing still I can put my hand in front of the vent and still feel the low breeze speed on my hand. As I drive in this setting the fan will randomly go from low to high, then back to low and keep doing that the whole time I am driving. Sometimes, when the fan switches to high it may stay on high for maybe 30 seconds or so and then quickly switch between low and high over and over again. Some times the fan will switch to high and stay there for a couple of minutes before changing back to its erratic speeds again. I recently had both my drive battery and the small one in the back (accessory battery) replaced, but all worked fine for over a couple month after that. I have checked all the fuses and relays in the box under the hood and all contacts are clean and and all have been tested and passed. What else could be causing the fan to act this way? Any thoughts would be greatly appreciated.