Had what we thought was a leak in the cooling system because coolant levels dropped in the reservoir. Took it to dealer and they say maybe a hiccup in the line when starting to use the rear heating. Got it back now noticing the engine temperature bounces all over the place. Ranging from 187-230. Differes from stop to start and stays a steady 195 while on the interstate. Noticed yesterday the fan won’t kick on even at 217 degrees when it should be kicking on by 185. I’ve looked for the cooling fan relay but can’t seem to find it. Any other ideas would be great. Also read it could be the coolant temp sensor but also having a hard time locating that. Never paid attention from the start whether the temperatures fluctuated that much but could it cause damage to anything with the temperatures bouncing back and fourth like that?