1999 Toyota Camry 3.0V6, 1MZ-FE. Because of recent hot weather 43C yesterday. Temperature went over 3/4 of temperature gauge approaching red line. Usually is slightly below 1/2 on gauge. This happened when drive and stop on 60Km/h roads with multiple traffic lights, with A/C on. The temperature will drop when A/C is off. It is fine when on highway even with A/C on. Found boiling + bubbling in the reservoir (fluid level is 10mm above the FULL line) when parked + idled by roadside. When A/C is turning, temperature was creeping up. Both fans are running full speed when the overheating occurred. Cap? hose (no leak)? radiator clogging?water pump? big air pocket (the red coolant was not flowing into the engine looking at the translucent coolant hose when bubbling)? air pressure in the radiator too high to take in coolant? Recently did a service and check, no leak on anything. Toyota service...since only they have empty slot to fill in before the holiday season. any suggestion will be greatly appreciated!