So my car started to overheat. I wasn't getting any hot air either!! I changed the thermostat and bled the air out at its highest point. it stopped overheating. When I drive the air is hot and when I'm idle it's cold.(no overheat) I had put the heat on full blast and I was realllllly driving it fast RPMs 3000-4000 range (NO OVERHEAT) so I let the car be because my belts were really crappy so I had to change them. Waited a day or so and changed both belts BUT. I drove it today and once I hit the highway it started to overheat. It also was blowing hot air while driving. And cold air at the stoplight (which is fine) did I not bleed the system enough??? I really can't tell what the problem is

Jroc2017 wrote:So my car started to overheat. I wasn't getting any hot air either!! I changed the thermostat and bled the air out at its highest point. it stopped overheating. When I drive the air is hot and when I'm idle it's cold.(no overheat) I had put the heat on full blast and I was realllllly driving it fast RPMs 3000-4000 range (NO OVERHEAT) so I let the car be because my belts were really crappy so I had to change them. Waited a day or so and changed both belts BUT. I drove it today and once I hit the highway it started to overheat. It also was blowing hot air while driving. And cold air at the stoplight (which is fine) did I not bleed the system enough??? I really can't tell what the problem is

Have you followed the troubleshooting steps in the FSM?

http://www.nicoclub.com/FSM/G35/Sedan/2004/co.pdf

See page CO-6

With a twelve year old vehicle when you changed the thermostat why didn't you replace the water pump, radiator, cap, coolant and belts all at the same time?

Are the fans running?
They may need replacement also?

Good luck

Telcoman

Clean any debris from in front of the condenser.