I have had an overheating problem for about 4 years. This happens only when its hot outside and when the AC is running. It doesn't overheat when the AC is not on. I first replaced the radiator cap... then I had the dealership flush the radiator... then I replaced the thermostat... then I replaced the water pump... yesterday I replaced the hoses that were extremely soft and when I replaced the hoses I noticed some really slimy black stuff that was in the hoses. My thought was that the hoses might be collapsing while I'm driving because they were so soft. The car is still overheating after replacing the hoses. I started thinking maybe that "melted rubber slime" from the hoses might be inside the radiator causing it to overheat. HELP

I would replace the radiator. There is likely unseen blockage of some of the passage ways, due to phosphate scale. Afterwards, refill with a 50/50 mixture of DexCool and distilled water. The link below may help:

https://www.askmehelpdesk.com/cars-t...tml#post235973

Change coolant every 3 years. With DexCool, it's important to keep the reservoir filled to the MAX Line and purge all air from the system.