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Old 01-16-2010, 05:46 PM   #1
hamrhed42
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cooling fan is always on?

i have a 160 t-stat and i have always been fine driving up and down the mountains here in hawaii now for some reason i cant get the cooling fan to shut off and warm up is being a bear. temp never goes over 160 but i need it hotter than that for normal running any input?
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Old 01-16-2010, 06:13 PM   #2
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i checked all the weiring and every thing seems to be in order im thinking the relay crapped out ill run to the parts store and get a replacement
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Old 01-16-2010, 11:43 PM   #3
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yes its going to be the relay , its not an expensive part, plus its time we begin changing out the older parts on these cars
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Old 01-19-2010, 05:53 PM   #4
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yea i put a new relay in and same thing i looked at the chitons/haynes and they dont really help
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Old 01-19-2010, 06:32 PM   #5
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Quote:
Originally Posted by El☠Diablo View Post
yes its going to be the relay
Not always
Check the pressure switch for the A/c.Turning A/c on ,automatically turns on the fan so if the switch is faulty or disconnected the computer will think the A/c is on and run the fans
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Old 01-19-2010, 08:54 PM   #6
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I had the same problem with my 87 along with other issues. I changed the relay, no change.
The ECM controls the fan on 87, so I changed the ECM hoping the other problems would also be cured at the same time. Bingo all problems went away!
THe car had sat outside for 2 years in the Oregon rain so it had running issues, like it would go into the "limp home mode" so by changing the ECM evrything came back to normal.
NAPA sells rebuilt ECM's for $89.00.
Good Luck!!
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Old 01-19-2010, 08:56 PM   #7
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like everyone else said its the relays, i had the same problem when i first bought my 94
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Old 01-19-2010, 09:41 PM   #8
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Quote:
Originally Posted by notaford View Post
like it would go into the "limp home mode"

Need to pull the codes, if in limp home mode fans will run as soon as key turned on

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like everyone else said its the relays,
Refer post #4
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Old 01-19-2010, 09:49 PM   #9
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Quote:
Originally Posted by hamrhed42 View Post
yea i put a new relay in and same thing
So relay not at fault.
Only way the relay can operate is if the control wire is to ground somewhere ; either through the ECM as it is supposed to be or by a short to ground in the control wire from relay to ECM.
As noted above ; ECM will turn on fans when in limp home mode or if the A/c pressure switch is open (A/c On )
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Old 01-20-2010, 12:00 AM   #10
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a/c switches and the ground faults ill check these tomorrow thanks for the help. lately i had to change out the maf relay because it went bad did that and reset the ecm and car runs great but the fan stays on any how im... im trying to get all this ricky-tick before i drop in new lifters and a stage 2 chip custom burnt. but if all else fails ill just install a stand alone thermo switch and call it a day
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Old 01-20-2010, 04:40 PM   #11
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unplug the fan switch on pass. side head between 6 &8 if fan stops change switch.
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Old 01-20-2010, 07:09 PM   #12
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Quote:
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unplug the fan switch on pass. side head between 6 &8 if fan stops change switch.

unplugging the switch normally STARTS the fan running, as the switch works by increasing ohm resistance as the heat increases, unplugging it sends a HIGH ohm and starts the fans
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
Old 01-20-2010, 07:10 PM   #13
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Quote:
Originally Posted by corvettelou View Post
unplug the fan switch on pass. side head between 6 &8 if fan stops change switch.

unplugging the switch normally STARTS the fan running, as the switch works by increasing ohm resistance as the heat increases, unplugging it sends a HIGH ohm and starts the fans
you might want to check if its currently un-plugged as that would explain the fan running
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
Old 01-20-2010, 09:45 PM   #14
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Quote:
Originally Posted by corvettelou View Post
unplug the fan switch on pass. side head between 6 &8 if fan stops change switch.
On '87 + models, the sensor between # 6 and 8 plugs is for temp gauge.
Fan switch is in other head between #1 and 3 (Only fitted if car has Aux fan option ) and has no connection to main fan if still factory wiring.Only ECM controls main fan operation

Quote:
Originally Posted by grumpyvette View Post
unplugging the switch normally STARTS the fan running, as the switch works by increasing ohm resistance as the heat increases, unplugging it sends a HIGH ohm and starts the fans
The stock Aux fan switch closes to ground at the preset (238 F ? ) temp.
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Old 01-12-2020, 02:02 AM   #15
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Sorry to pull up an old thread but this was one of a few that came up for a C4 and helped with finding my problem. Hope this helps for a reference for others.



A/C condenser fan switch is the proper name. I found one of the metal spade connectors pushed down not making contact.



When searching and replacing the relay did not work, this led me to believe the switch was bad but found this.



All I need is a new pig tail from rock auto. Switch is available as well.
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