Hi Guys, need some advice.
Having some overheating problems, I have a 04 camry 2.0

The mechanic said that the a/c fan and rediator fan has two speed and runs depending on the temperature. but runs on a lowspeed instead of needed highspeed once the car reaches above optimum operating temperature that's why the car overheats.

This only happens when i've been driving long or stuck in traffic in the middle of the day, upon checking i can see that both fun runs a little low. the overheating calms down when i run at a cruising speed.

In the normal city driving, everything is ok the fun runs both on high and low.

thermostat or relay?