normal temp? both hot side and cold side

[Fenvy]

I have gathered that the optimal coolant temp is about 175 to 180F

I have also gathered that half of the poeple install their aftermarket temp sensor on the hot side (top) while the other half install the temp sensor on the cold side (bottom).

To be on the same terms, I want to define my questions using farenheit as unit and top side as source of temp taken because like someone else said, lower side temp pretty much just show how efficient your radiator is.

My temp sensor is mounted on the top side and according to the reading, it's about 195 to 210F. However, when I turn on the AC the reading goes to around 250F.

I don;t think that's normal, is it? How can I remedy the problem?

[ILikeMy240sx]

Did you check the AC fan thats supposed come on with the AC on?

Turning the AC on puts more load on the engine so if nothing is doing to cool down that extra load I guess your observation makes sense.

[Fenvy]

ac fan? wow I never heard of that... know where I can find this little unit?

[ILikeMy240sx]

Its a small electric fan right in front of your mechanical fan.. Turn your AC on and see if that sucker is spinning. As for where to find it... junk yards

[Fenvy]

I don't have a mechanical fan though, I have flex a lite eletric fan that's on all the time