Chrysler Repair: 1996 Chrysler Cirrus w/ 4 cyl., water pump impeller, 1996 chrysler cirrus

Question
My temperature gauge goes up when my ac is running. I have had the thermostat replaced and the radiator flushed out. My fans are coming on also, so what else could be the problem? It only does this when I'm sitting idle but when i start going the temperature hand goes back to normal. If I am sitting idle with the ac off the temperature hand stays normal. Could it be a sensor has gone bad?

Answer
Hello Donald,
I would not be surprised that the temperature gauge goes up under the conditions that you describe. The question is whether it rises to the point of blow off of steam from the coolant recovery bottle or not. If not, then I would not be concerned about it. You have satisfied yourself that the thermostat and radiator are in good condition, so this more than likely represents the normal variability to be expected when the heat dissipation demand is high and the cooling capacity is reduced due to standing still. About the only other possibilities are that the mixture of coolant is not 50-50, that the water pump impeller blades are compromised in some manner, or there is air trapped in the cooling system in the vicinity of the thermostat housing. Is this a marked change since the car was new? If you will tell me which size 4 cyl engine you have I'll check the manual to see if there is any trick involved in refilling the system to minimize air bubbles (as was the case with the earlier Chrysler 4 cyl. engines of the '80's and early 90's).
Roland