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1975 Eldorado "coolant temp" light on

Started by ghhatley, September 17, 2015, 08:03:30 PM

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ghhatley

Coolant temp light has decided to come on and not go off. Car is cool and so is the coolant yet light stays on. I just replaced the upper radiator hose and topped  the coolant in tank. Any ideas? Any ideas how to fix it?
Thanks
Garage:
1958 Continental Convertible
1958 Continental Convertible
1958 Cadillac Extended Deck gone
1958 Cadillac Fleetwood 60 S
1960 Continental Convertible
1967 Continental Convertible
1973 Eldorado Convertible
1975 Eldorado Convertible aka Cabernet Caddy

Scot Minesinger

The light on dash is energized by the sensor making ground with block.  It is located right under the a/c compressor with a green wire.  The wire may have compromised insulation and grounding before sensor.  This would especially be true if it is more faint.  Trace the wire and see if it is a problem.

This advice is given trusting that of course the this is a false alarm.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Bobby B

Quote from: Scot Minesinger on September 17, 2015, 08:08:26 PM
The light on dash is energized by the sensor making ground with block.  It is located right under the a/c compressor with a green wire.  The wire may have compromised insulation and grounding before sensor.  This would especially be true if it is more faint.  Trace the wire and see if it is a problem.

This advice is given trusting that of course the this is a false alarm.

Good Advice….Disconnect the sensor and see if the light goes off. If it does, go get yourself a new sensor. Cheap Insurance…..
                                                                                                                                                             Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

Scot Minesinger

If you do have to remove the sensor the compressor can be removed as per instructions in the shop manual without interrupting the refrigeration circuit.  Remove five bolts anchoring compressor to intake manifold after loosening belts.  Disconnect electric clutch wires.  With air cleaner housing removed and pad on passenger side inner fender, lift compressor up and out to rest on the pad on top of passenger inner fender.  Then you can get to sensor without messing with the refrigeration circuit.  I did some valve work this way and a/c worked great before and after.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

ghhatley

Garage:
1958 Continental Convertible
1958 Continental Convertible
1958 Cadillac Extended Deck gone
1958 Cadillac Fleetwood 60 S
1960 Continental Convertible
1967 Continental Convertible
1973 Eldorado Convertible
1975 Eldorado Convertible aka Cabernet Caddy

RobW

Has anyone done work on the heads? There is a sensor on each head. They look exactly the same but do two completely different things. One is the sensor that delays the heat coming on until the engine warms up. If this sensor is mounted where the actual temp sensor to warn of overheating is mounted it will turn on the light and buzzer once the car warms up and will keep it it on.
Rob Wirsing