So my car starts to overheat when I'm at a stop and cools when I start moving. Also I have replaced radiator and cap , thermostat, water lines. When I fill up the radiator it last for a while until it overheats I check and the radiator is empty and has no antifreeze there are no leaks what can it be? Thanks.

 

When I touch the radiator cap its not really hot

 

You need to buy a compression tester and do a compression test to check if the head gasket is leaking.

 

^x2

Do you see any white smoke out the exhaust while at idle or driving around?

If you want, you could remove your spark plugs and see what they look like. If any of them are really clean and shiny. That is a good indication of a head gasket failure as the spark plugs are basically steam cleaned.

Could also do a pressure test on the coolant system.

I usually remove the rad cap, install the pressure tester, start the car and let it get up to operating temperature (fans cycle twice). Then shut the car off and pump up the coolant system pressure tester to 16-18psi, if it's not already up to that pressure. Then sit and watch for leaks and/or a pressure drop on the gauge. If the pressure drops, there is a leak somewhere that you will have to find.

 

^^It could be a leak that only happens while driving, like one of the small hoses around the intake manifold

 

I changed the head gasket and the spark plugs and wires. I see a leak but I'm not sure where its leaking from. I don't see it leaking from water pump and the radiator is new. If my engine is over heating then why is my ac still cold? Thanks.

 

I agree. That is why I mentioned doing a running engine (hot engine) coolant system test. It allows all of the fluid to heat up and all of the hoses and fittings to expand to there fullest.

You will have to find that leak. What area of the engine bay do you see the leak? There are a number of coolant pipes and hoses under the intake manifold.

The AC is a completely separate system from the engine cooling system/heater core.

 

Head gaskets don't just leak, they leak because the head and/or block warps. You can't just replace the head gasket and expect everything to be ok.