Driver side radiator fan is not working and car is overheating

Tiny
JOSHPB
  • MEMBER
  • 1999 CADILLAC DEVILLE
  • 4.6L
  • V8
  • AUTOMATIC
  • 102,000 MILES
My car is overheating, much seen thread. I noticed that the driver side radiator fan is not on. I am looking for any indication other than a blown head gasket as to why it is not on. The reservoir tank is full just flushed, new upper radiator hose. I have seen threads on purge lines could that be connected to my problem? I am trying to figure all this out without going into a shop due to financial issues at the moment. Please help. Much appreciated.
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Thursday, October 20th, 2016 AT 12:57 PM

53 Replies

Tiny
HMAC300
  • EXPERT
Check fuses and relay for fans in under hood fuse box. then check for a bad connection or bad fan. Here is a guide to help check for power and the fan wiring diagrams so you can see how the system works.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.
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Thursday, October 20th, 2016 AT 3:47 PM
Tiny
JOSHPB
  • MEMBER
Thank you I will for surely take a look at them. Just for reassurance purposes would a water pump, thermostat, purge line be a cause for the fan not to be moving? I have a lot of people in my ear saying this and that, which is fine I like to be able to look into anything helpful. I saw on a video a man cleaned a metal tube that was connected to the reservoir tank. It was completely clogged. Any connection to the fan? And one more question for now, are both fans supposed to be on when I start the car? I have heard both, yes they are, and no they turn on at different temperatures.
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Friday, October 21st, 2016 AT 10:47 AM
Tiny
AL514
  • EXPERT
If your car is over heating both fans should be running, both fans should also be running if you turn the A/C on. Try the A/C if only one fan is still running there is either a problem with one of the three fan relays or the fan motor itself has gone bad.

There is a 50 amp maxi fuse (#7 in 2nd diagram) which powers both fans on two different circuits. This fuse is located in the engine compartment and neither fan would run if this fuse was blown. You can easily check each fan for power with a test light. Right fan has power on light blue wire and Left fan has power on black wire.

The ECM commands when each fan comes on. It does not command both fan unless A/C is on or excessive temps are reached. If both fans were always on the car would cool too fast and harder for the ECM to keep it within operating temperatures.
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Friday, October 21st, 2016 AT 3:50 PM
Tiny
CAT4690
  • MEMBER
  • 1999 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 107,000 MILES
My cooling fans are not working on my car, I hooked up my fans directly to my battery to check the motor and the motors are good. Idk what else it could be or how to fix it. Also I went to advanced auto parts and had my engine diagnosed and I had a code of P1660 it said Factory Controlled Auxiliary Input/ Auxiliary Output. But that could be anything? Does anyone know what it means exactly?
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
BLUELIGHTNIN6
  • EXPERT
DTC P1660 : Cooling Fan Control Circuits

Test cooling fan relay(s), fuse(s) and engine coolant temperature sensor.
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
JIMMY PHILLIPS
  • MEMBER
  • 1999 CADILLAC DEVILLE
  • V8
  • 2WD
  • AUTOMATIC
1999 cadillac deville the electric cooling fans are not working but the motors are good. Could it be the sensors and where are they located
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
FACTORYJACK
  • EXPERT
The coolant temp sensor is in the rear cylinder head, at the transmission end, under the EGR vlve area. It is wired to the engine control module(or PCM), and the PCM controls the cooling fans through relays. The relayes are down under the fans, mounted to the lower core support. When you turn on the A/C, first of all does the compressor come on, and if so do the fans come on then?
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
CARRO
  • MEMBER
  • 1998 CADILLAC DEVILLE
Engine Cooling problem
1998 Cadillac Deville V8 Automatic 105000 miles

I Think the cooling fan is not working, when should the cooling fan turn on? Does it turn on at a certain temperature? Because I drove it one day and the temperature of coolant stayed around 197, but when I got home, I let it run for a little, and the tempetrature started riseing just past 210, (i turned car off) and I looked to see if fan was on, but it was not on.
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
2CEXPT
  • EXPERT
The fan should come On at 195-215degs -check and test the fan motor, fan relay, coolant temperature sensor and if it has an engine temperature gauge switch check that too.
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
IMAQUESTIONMAN
  • MEMBER
  • 1997 CADILLAC DEVILLE
  • 4.6L
  • V8
  • FWD
  • AUTOMATIC
  • 170,000 MILES
Under normal driving conditions my 97 Cadillac Deville's coolant temp runs at about 190-192F. Experts say that that 190 up to 205 is a normal operating temp. If that is a normal operating temp for the engine then why is it set so that the high speed fan doesn't come on till the coolant temp hits 234 and rising? The the most catastrophic thing that can happen to an engine is for it to over heat. Why wait till just before overheating to turn the fan on? Why tempt fate? If it's good for it to run in the 230's then why does it normally run at 190 to 205? Splain Lucy.
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Tuesday, November 26th, 2019 AT 6:43 PM (Merged)
Tiny
HMAC300
  • EXPERT
If it gets to 230 degrees under certain circumstances is no big deal when fan kicks on. Coolant is under pressure so it takes a bit more before it overheats. And when it hits that temp to kick on fan it usually brings it down to normal range.
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Tuesday, November 26th, 2019 AT 6:44 PM (Merged)
Tiny
VOCALPOINT
  • MEMBER
  • 1995 CADILLAC DEVILLE
  • 135 MILES
Is there other fuses the car runs hot I've noticed that the fans did not come on. Coolant is backing up in the overflow the coolant fans are not coming on at all?
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Tuesday, November 26th, 2019 AT 6:44 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
The fans will come on when the temp reaches around 209 degrees for the cooling system and when the ac is on and the high side is 150 lb or higher.

I would start with checking the thermostat. It may be closed all the time. If you have driven this overheated, you may have done internal damage to the head gaskets.

There are many reasons for this, such as a bad rad cap, clogged radiator water pump failure and lastly, blown head gasket.

Roy
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Tuesday, November 26th, 2019 AT 6:44 PM (Merged)
Tiny
DICKWHYTE
  • MEMBER
  • 1994 CADILLAC DEVILLE
I have a 4.9 engine with 150,000 miles. The cooling fan will not come on. I have changed the sensor but it still will not come on. What should I do?
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Tuesday, November 26th, 2019 AT 6:44 PM (Merged)
Tiny
BUZZSAW
  • MEMBER
Hello,

There are three cooling fan relays and a 50 amp maxi fuse that needs to be checked. Here is a guide to help you do some testing with a wiring diagram so you can see how the system works:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

Cheers
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Tuesday, November 26th, 2019 AT 6:44 PM (Merged)
Tiny
BISCUIT
  • MEMBER
I had this problem it ending up being the coolant fan relays and the fan motor. FYI
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Tuesday, November 26th, 2019 AT 6:44 PM (Merged)
Tiny
KMEYER78
  • MEMBER
  • 1998 CADILLAC DEVILLE
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 155,000 MILES
My car is overheating it is a 98 Cadillac Deville I believe it is the fans I let it idle up to 221 degrees and the 2 electric fans did not kick on I am assuming the fans should kick on around 200 degrees the only fuse box I can find in the car is under the hood on the drivers side and I can not find a fuse for those fans. Is there a second fuse box that I have not been able to locate? Is there even a fuse for those fans? I would appreciate any help you can give me thanks
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Monday, June 1st, 2020 AT 2:38 PM (Merged)
Tiny
HMAC300
  • EXPERT
See pic right maxi fuse center under hood fuse box driver'sside. Relays where they say they are there are three of them
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Monday, June 1st, 2020 AT 2:38 PM (Merged)
Tiny
JOSBRENNAN
  • MEMBER
  • 1998 CADILLAC DEVILLE
  • 111,000 MILES
I never hear the fans come on
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Monday, June 1st, 2020 AT 2:38 PM (Merged)
Tiny
2CEXPT
  • EXPERT
Haven't heard it-check and test the fan motor, the coolant temperature sensor and fan relay
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Monday, June 1st, 2020 AT 2:38 PM (Merged)

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