So, my xb tried to overheat on me last night. I have an ultragauge that I monitor the engine temps with and it has always stayed at 185 no matter what the conditions were. Last night I was driving home in some stop and go traffic and the temp climed to over 200. I was almost home so I just turned on the heater, the temp dropped and I parked it. I came out this morning and did a visual inspection and could not find any leaks and the radiator was full. I started the car and let it idle until the temps started to climb into the 200's again. I didn't think my fan was kicking on, so I turned on the a/c and the fan kicked on and the temps dropped. I decided to drive some more. As long as I'm moving the temps stay relatively fine. At a stop, or under heavy load like going up hill the temps will start to climb. All of this is based off of what my UG is telling me, I haven't triggered the actual temp light yet and have no CEL or trouble codes. When exactly is the fan supposed to be kicking on and what should I check if it isn't? It doesn't seem like that's my only problem though since the temps will also start to climb when I'm moving, but under load. I just turned 94,000 so I'm sure I'm probably due for a water pump as well. Any other ideas or suggestions? Thanks.