You may have a failing thermostat, it can have deposits that are built up over time preventing proper water flow. When your air conditioning is on it causes more of a load on the engine due to the compressor running.
I would recommend that you have your coolant system checked. It is possible that your coolant is low or needs to be flushed or that there is a problem within the system.
When you use the a/c is makes the engine work a little harder and if a coolant problem is developing it would become more evident when using the a/c.
The easiest thing to do is check the coolant reservoir bottle and see if it is low. If you haven*t had a coolant replacement in 30,000 miles you should do that as well. Check your owner*s manual for where to add coolant. Make sure that you always add a 50/50 mix of coolant and water. You should also check your owner*s manual for the proper type of coolant. You may need to purchase this from a dealer. Hope this helps.
〉 Answered on Jun 17th, 2009 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines
Normal is usually mid way for most cars. It is normal that the Temp rises with A/C on. Check with the manufacturer if you think it is higher than in the past
〉 Answered on Jul 7th, 2009 by Patricia Algier , Owner at Valley Dealer Exchange Inc