Cooling fans not working

Tiny
RTRAVERS
  • MEMBER
  • 2001 CHEVROLET MONTE CARLO
The fans do not work unless the AC is on. Seen so many similar posts with no definite answer. Is it the engine coolant temperature sensor, the thermostat, the head gasket, the relays? I am pretty sure it is not my temperature sensor or the relays. The thermostat was supposedly replaced shortly before I bought the car and I would think this is an electric problem. Current status of the car is it over heats when the AC is not on to about a quarter above half line then goes down and back up. I have not been in city traffic yet this summer so I have a feeling if I sit in traffic it would definitely increase without the fans. As is right now I am just going to keep the AC on but would really love to fix this. Thanks for any responses in advance.
Thursday, May 26th, 2011 AT 10:32 PM

11 Replies

Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
You cannot rule anything out without testing it. The coolant sensor could be bad, causing this or it may be a faulty relay.
Check out the guide below on how to test a relay as well as the wiring diagram below
Let us know what you find.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
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Friday, May 27th, 2011 AT 5:15 AM
Tiny
BUCKWELL262
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 75,000 MILES
I noticed my car running hot at idle and in traffic. I checked the fuses and electric cooling fans for obstructions and nothing. I tried turning on the AC to see if that would work and nothing. I do not know how to check to see if it is a relay issue. I do not want to buy new relays or sensors unless I need to. Any advice would be appreciated. Thank you for your time!
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
BILLYBOBASAN
  • MEMBER
  • 13 POSTS
Unplug the two wire connector from cooling fan, connect test light to the two wires, start engine and turned on A/C, if tester lights up, replace cooling fan motor. If it does not find the relay. There are usually a couple that are just alike, swap one temporarily and if that fixes it swap them back and get a new one. Do not forget to plug two wires back into fan motor when doing this test!
Hope this helps,
Billybob
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
CHUCK TENN
  • MEMBER
  • 1 POST
  • 1996 CHEVROLET MONTE CARLO
Six cylinder, front wheel drive, 70,000 miles.

Hi, the electric radiator fans in my car are not working, and the engine is running hot. I have already replaced the relays. Is there a sensor or anything else the controls these fans that I should replace as well?
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
RENAUDTN
  • MECHANIC
  • 636 POSTS
Hello there,
A few things can prevent your fan from working:
- bad relay (you checked that already from what I understand)
- bad fan motor: does your fan come on when your car is idling and you turn on the AC on full blast? If not you could have a bad motor or a problem in the circuit. If it does, your motor as well as your relay, fuse, connector etc are fine.
Also, you can check for a bad motor by unplugging the connector at the motor and connect the fan motor directly to your battery with a set of jumpers. If fan comes on, your motor is good. If not, you either have a bad motor or you have a problem in the circuit.
- problem in the circuit: bad ground, bad/corroded connector, blown fuse, etc Use a wiring diagram and a DVOM to check the circuit.
- bad sensor: on some models the fans are activated by the coolant sensor, on other by a temperature switch. I don't know which one you have, but check in a manual (Haynes, Chilton) and follow their procedure to troubleshoot the sensor that runs the fan.
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
JAMESNGA.
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 125,374 MILES
Engine overheats with AC on. Cooling fans not coming on when AC is turned on. Fans work when 12 volts jumped straight to them. Relays in box on passenger fender well but description and small writing worn away. Help please.
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Since cooling fans not coming on with A/C it indicates either Freon charge is low or relay is bad. I have attached wiring diagram of cooling fans below.
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
LARRYDEADBEATSQUARE
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET MONTE CARLO
  • 3.1L
  • V6
  • FWD
  • AUTOMATIC
  • 150,000 MILES
I have replaced thermostat. Electric cooling fans for radiator run when AC is turned on. If I unhook the temperature sending unit both fans run continuously. I have replaced the temperature sending unit. When I disconnect the temperature sending unit the temperature gauge in the car does not work. Surprise. Water pump seems to be working. With everything hooked up normal when engine is started and allowed to warm up, cooling fans do not come on like they should and then it overheats. Any help would be great.
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Stop unplugging the coolant sensor. That messes up all kinds of things, especially the fuel mixture. Turn the AC on and see if the fans come on. If they do, your system is just fine. It is supposed to get hotter when slowed or stopped. These fans are not programmed to come on until approximately 226 degrees which may seem too hot to you but that is exactly they way they were designed to work.
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
KARENKELLEY
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET MONTE CARLO
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 60,000 MILES
My cooling fan runs after I shut my car off and the temperature gauge is not working but my heat still works. Took the cover off the radiator right after I got home and it was not steaming.
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Is the check engine light coming on at all?
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Wednesday, September 12th, 2018 AT 7:07 PM (Merged)

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