Just got an 84z28. When i idle it can run up to about 240-250! When i'm on the highway i'm good at between 190-220. But when i turn my AC on at idle it cools down! Isn't that a bit backward sounding?

 

I think when the a/c is turned on that both fans run if you have a dual fan setup. My car used to run those temps at idle in these hot Texas temps but I grounded the relays for both fans so they run continous while the engine is running. This keeps my temps from 195* and 210* at the hottest idling with or without a/c on and a 195* stock thermostat. I have my secondary fan relay ground on a toggle switch so during the winter months I can have control if the engine starts to run to cool and also to let the engine warm up faster in the morning so the heater will work faster. Some people say this puts a strain on the alternator and will make it go out faster but the way I look at it is that when I buy an alternator I make sure it has a lifetime warranty. Also an alternator is alot cheaper than a engine or transmission. Hope this helps you. John

 

aaah! I wonder if I have a dual fan set up. But even if I do, it shouldn't get that hot? Thanks man....

 

Check to see if you have dual fans. If so the primary fan should come on once the car reaches 195* and is going less than 35mph. What might be causing high idle is the fan motor in your primary fan might be blown. The secondary fan comes on with the AC or when the car reaches extreme temperatures. Run your car for a bit so it is warm then pull over with the car running and see if the primary fan is on. Should be the fan to the right when looking at the car from the front.