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cooling fans wont come on


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mikeatpriestlake
User

Nov 11, 2014, 11:23 PM

Post #1 of 6 (1248 views)
cooling fans wont come on Sign In

ok this is a toughie, at least for me. I have a 91 Chevrolet Lumina sedan. 3.1 v6, 160000miles. The cooling fans don't come on. I have replaced the coolant temp sensor, and all the relays are good, tested by a reliable source. Both fans work, I hooked them up to the battery and tested them. They wont come on for any reason...unless. If I scan for codes on the obd1 computer by using the paper clip trick, the fans come on. as soon as I hook up the paper clip they come on and as soon as I take it out they go off. I even tried jumper wire on the temp sensor. nothing works. any help would be great. BTW, the car is hesitating and missing. I got a code for a tps and replaced it, but it still does the same thing only a little worse. don't know if the two are related but thought I better mention. The car has also passed a combustion leak test. Is it possible that there is something to do with the a/c? It hasn't worked for 2 years, but the cooling fan thing is new. any help would be appreciated.


Hammer Time
Ultimate Carjunky / Moderator
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Nov 12, 2014, 3:18 AM

Post #2 of 6 (1240 views)
Re: cooling fans wont come on Sign In

The fact that they come on when in diagnostic mode proves that the circuit is in working order and the computer has control. I suspect you just don't understand how these fans are programmed to work. They are not designed to even come on until the temp reaches the 227 degree range for the primary and 245 for the secondary fan which may seem very hot to you but that is the program for these.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 12, 2014, 3:19 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 12, 2014, 5:14 AM

Post #3 of 6 (1231 views)
Re: cooling fans wont come on Sign In

Totally agree with HT this may be normal and why are you just noticing this now is a question? Most areas about now barely ever need the electric fans - vehicle and driving conditions vary of course. About this vintage GMs I did notice zero fans if not using A/C or defrost settings unless perhaps coming to a quick stop after a long run at highway speeds then then sudden stop and go they would kick on for a while and still quit - all normal.


It would bug me too to watch a creeping up there temp gauge and at the age now I would check by touchless thermometer that the actual engine temp was in line - right at thermostat should be about what engine is inside.


With about any check that radiator and this with a condenser in front of it is clean of bugs, leaves or debris of any sort -- some you need to take off a part up top to see in between them.


If somehow this is exceeding temps HT posted for this then really look into why they don't come on. Pretty sure that if A/C isn't engaging clutch any more the fans will NOT come on like they would if it was operational but should be fine just don't have A/C when and if you did want it,


T



(This post was edited by Tom Greenleaf on Nov 12, 2014, 5:19 AM)


mikeatpriestlake
User

Nov 12, 2014, 2:51 PM

Post #4 of 6 (1195 views)
Re: cooling fans wont come on Sign In

It is possible that i don;t understand how they work, but they NEVER come on. They worked up until just a while ago, but the a/c hasnt worked in a couple years. if they never come on are you saying that they just arent needed? once or twice this summer the car temp light came on and got very close to overheating. turns out i needed to replace the water pump, it was leaking while driving. it wasnt til after this that i realized the fans werent coming on. ever.


Hammer Time
Ultimate Carjunky / Moderator
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Nov 12, 2014, 5:00 PM

Post #5 of 6 (1193 views)
Re: cooling fans wont come on Sign In

As I already told you, the primary fan comes on at 227 degrees. If the car is moving, it will never reach that temp. If the car is stopped or in traffic, it could.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 12, 2014, 10:50 PM

Post #6 of 6 (1181 views)
Re: cooling fans wont come on Sign In

Yes to it is possible to plain not need the fans! Just a less than hot day and any breeze even sitting still might not need the fans. Winter temps they'll probably never come on and that's normal.


If worried - run heater and feel the air. If/when it no longer blows hot air at floor you are either overheating or low on coolant short of any other problems that's a clue of real trouble with engine temperature,


T



(This post was edited by Tom Greenleaf on Nov 12, 2014, 10:51 PM)






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