Radiator Fans Come on at ON position - even cold engine

kohokohoJune 13, 2009

I recently purchased a 96 Camry LE and I am having engine overheating problems, on the highway. One of the strange things I have noticed is that even when the car is parked inside the Garage for a whole day (cold engine), when the Key is put at the "ON" position without the A/C on or without starting the engine, both radiator fans will come on.

What could be the problem? I feel this particular problem should be an easy fix, although I've probably got other problems since the engine does over heat when driving for 15-20 min on the highway @70mph. It will not overheat while driving around town.

I took it to a shop where they did a leak test and apparently found no leaks. What should I get checked next, without breaking $$?

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Normally when the fans run all of the time, its because the car was overheating, and someone didn't know how to really fix it, so they rig the fans. Overheating on the highway is usually an airflow, or coolant flow problem. Once your over 25mph, you don't need the fans (that's why they are electric) because you already have more air pushing through the radiator and AC condenser than the fans would ever pull.

The way I approach a problem like this is drive the vehicle and get it to start heating up. Then I stop and start measuring the surface temperatures of different parts of the radiator, and engine block and cylinder head. If airflow is the problem, everything will be hot. If coolant flow is the problem, then the cylinder head will be the hottest. The top of the radiator will be reasonably close to the same temperature of the cylinder head. Meanwhile portions of the engine block, and especially portions of the radiator, especially the lower hose will be much cooler than the cylinder head.

The causes could be; Debris inside of or inbetween the AC condenser and/or radiator blocking full air flow. Missing or damaged under car air dam or baffles. Low coolant level. It may be full in the radiator, but that does not mean an air-pocket isn't trapped in the engine. Bad thermostat. Unlikely actually, in fact most thermostats when replaced for overheating appear to fix the car when in fact the problem was actually low coolant. A water pump impeller worn or broken. This causes the coolant to not move the through the engine and the radiator as quickly as it should. A missing thermostat. That one takes a long time to explain, but essentially the coolant "short circuits" the engine and some of it sees cold coolant from the radiator, and some of it stops circulating and overheats. Lastly a restriction in a hose or the radiator itself could be the cause. It takes time to test this out just like any other problem a vehicle can develop.

    Bookmark   June 15, 2009 at 3:33PM
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Or why not just run the engine from cold to hot without the radiator cap on and watch to see if it flows????????????? Just like the locked up 350 chevy topic, here again is a FICTICOUS topic and was answered with a counter salesmen type answer above.

    Bookmark   June 20, 2009 at 3:39AM
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