Heating problem
 

Hi i have an 04 rx8 and I have a heating problem whit it I already put a new thermostat and new radiator and it still heating.I don't know what else could be the raditor fan is working well they told me it could be the radiator cap because I does not have the original one but I will like to have some advises from rx8 owners if you could help me please. Thank u

What temps are you seeing and under what conditions?

If it were the radiator cap, it would be quite noticeable. i.e. steam coming out of the cap. but if that were the case then that would be helping your cooling system to lose heat, so I am not sure why they told you that could be the problem. Have you checked your hose connections for clogging? If the car is warm and the thermostat is open, then the hoses should be hard because they are circulating coolant. Other than that, are you running 50/50 (half water half coolant)? Are you having a loss of coolant?

Sometimes it goes all the way to redline.

You mean the coolant temp goes all the way to the 'H'?
If so, I would inspect the water pump pulley while the car is idling and see if its seized or slipping.
Maybe even remove the drive belt from the pulley and spin it to see how it feels.

The AC in my car is always on the green light, even when its off...

when its turned off, should any light be on??

this thread closed. continued in his other thread about the same problem https://www.rx8club.com/series-i-trouble-shooting-95/overheating-200530/