Expert: Rob Painter - 8/10/2011

Question
I need to find the cooling fan sensor switch on my fleetwood. been told it is on the motor , on the radiator , ect... None of the above is right !

Answer
Hello,

Sorry, car is too old for me to tell you the exact location. Have seen in radiator and in the engine, however, I personally have never seen a sensor fail and relays are rare to fail as well, but you have an aluminum engine notorious for over heating issues and when they overheat even a little bit, the engine is self destructing.

Before you play with the sensor and chase ghosts, you need to run a pressure test on the cooling system and the cap. Needs 15 pounds to circulate. Head gaskets are notorious to blow in these engines from overheating, never the cause, but the effect. Heads crack because of over heating, engine blocks crack.
There are three symptoms that have to be checked for. Coolant in the oil (milky color), white smoke coming from exhaust and an external leak at the head or the block.
The cooling jackets are small and very easily plugged. Something as minor as old gasked material inside  the engine will plug it.
The only time I have run into a bad sensor was it was filled with stop leak which should never be put into this engine.

You may know this, but to check the fan operation, engine off and a/c put in max or defrost, fans should come on in a minute and that way you know the relays are good.
Fans only run in city driving and radiator takes over at highway speed.
The system may have to be flushed too. 5 years is the absolute max on coolant!

I have written about these engines and overheating over 100 times. It's a great engine for economy and performance, but over heated you can be looking at thousands of dollars to repair and you are not going to find a used Caddy aluminum engine that has not been overheated.

Before you jump into finding the sensor, you need to tke all the things I told you into consideration. If the system is not circulating (Very common) the sensor is dry and not calculating engine coolant heat.
Although I could not answer your question directly, I hope I have given you some guidance.

Good luck!

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