Engine Cooling problem
1998 Dodge Caravan 6 cyl Front Wheel Drive 216000 miles
My 98 dodge Grand Caravan 3.3 engine has developed an odd problem. The engine is overheating at random times mostly when the AC is on but without also. The problem seems to appear in stop and go traffic. Some days it will run without problems. I live in AZ and it is over 100F every day here The car run well in any temperatures until recently.
I have owned this car since new and have replaced many parts and in the past two years also the radiator, fan assembly, just replaced for the fourth time the Fan relay and harness, water pump is one year old. Thermostat is also new. When overheating the Fans are running at full blast regardless of that if the AC is on the temperature starts climbing rapidly. Coolant is clean and fresh there is no debris in it. I have done a pressure test on the cooling system No leaks. There is no oil in the coolant or white smoke from the exhaust. I already did a leak down test on the engine everything checks out OK. Any ideas?