'73 Coupe de Ville "water" light coming on

[cadillac73]

Hello all,
My "water" light came on this morning...checked the level and it was a little low so I added some coolant.  Light still comes on, but only at idle or low rpm.  Water appears to be circulating, and it is not overheating.  Could it be a wonky sensor?

[TJ Hopland]

The water light is a coolant temp sensor.  Its located under the AC compressor.   Original spec was something like 240* range which is a decent window above the 200-220 these normally run at. 

Making sure there is coolant is a good first step.   Second step would be to get one of those IR temp guns and probe around to see what the coolant temps actually are.  They are pretty cheap now and handy to have around.   You may find they are high and you need to look further into the health of the cooling system.  If they are normal 200-220 then you have a bad sensor or damaged wire.   It runs in the harness on top of the engine along the drivers side so a look there to make sure nothing looks pinched or melted.   If it does turn out to be the sensor you can unbolt the compressor and swing it out of the way without distributing the hoses.     

[cadillac73]

Thanks very much...I will do as you suggested!!

[cadillac73]

So one of these things you mean?

https://www.amazon.com/dp/B01FYVEJMY/ref=asc_df_B01FYVEJMY5081095/?tag=hyprod-20&creative=395033&creativeASIN=B01FYVEJMY&linkCode=df0&hvadid=167130088685&hvpos=1o4&hvnetw=g&hvrand=13818707502142839215&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9002628&hvtargid=pla-305891437342

[TJ Hopland]

That tool should work.   Good price too especially if you are a prime member.