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| Cooling System Trouble Shooting (Page 1/3) |
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Aaron.Russell
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JUN 27, 02:22 PM
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Hey guys, I have a 85 V6 GT.
The car has an aftermarket radiator and electric fan.
No matter what I do I can't seem to get the fan to turn on at temperature.
I know the fan works, I can get it to turn on with the A/C and jumping the big fan relay.
I've tried with and without 2 different thermostats, it has had 3 different fan switches as well.
The car currently sits with the nose very slightly down in the driveway. Coolant is completely full at the radiator side, thermostat side, and in the overflow. Is it possible air in the system and causing this? The heater blows hot.
I did follow Ogre's fill procedure on the cave.
I believe that the temp gauge works properly, as the sending unit was replaced at some point and it seems to warm up at the rate I would expect.
Thank you in advance. I've been chasing this around in circles with no progress.
EDIT: The fan turns on when grounding the fan switch wire.
The connector for the fan switch as also been replaced[This message has been edited by Aaron.Russell (edited 06-27-2024).]
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Patrick
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JUN 27, 02:58 PM
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Will the fan turn on if you ground the wire that goes to the fan switch?
If it doesn't, then I'd suspect a break in the wire somewhere in the harness.
If it does, then either the fan switch is faulty, or it's not able to ground itself properly due to perhaps too much Teflon tape being used on the threads.[This message has been edited by Patrick (edited 06-27-2024).]
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Aaron.Russell
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JUN 27, 03:07 PM
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| quote | Originally posted by Patrick:
Will the fan turn on if you ground the wire that goes to the fan switch?
If it doesn't, then I'd suspect a break in the wire somewhere in the harness.
If it does, then either the fan switch is faulty, or it's not able to ground itself properly due to perhaps too much Teflon tape being used on the threads.
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Yes, I forgot to mention that one. The fan DOES turn on when I ground the fan switch.
I don't think the fan switch is faulty, as I have used 3 different ones. I have not put any Teflon tape on threads of any of them. Is corrosion on the female side of the threads a possibility in your opinion then?
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Patrick
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JUN 27, 03:15 PM
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If the fan turns on when you ground that wire, it then means one of two things... either the switch(es) are faulty, or for whatever reason, the body of the switch isn't able to ground out to the intake/block.
Using a multimeter, test the continuity from the body of the fan switch to the block. There should be little to no resistance.
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Vintage-Nut
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JUN 27, 03:42 PM
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85-86 Coolant Fan Schematic
------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles
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Aaron.Russell
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JUN 27, 04:07 PM
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| quote | Originally posted by Patrick:
If the fan turns on when you ground that wire, it then means one of two things... either the switch(es) are faulty, or for whatever reason, the body of the switch isn't able to ground out to the intake/block.
Using a multimeter, test the continuity from the body of the fan switch to the block. There should be little to no resistance. |
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Just went out and tested the resistance. Got 1.4ohms. Does this seem like the proper amount? I do have one of the old switches, should I throw it in and compare resistances?
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olejoedad
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JUN 27, 04:26 PM
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That resistance value is ok.
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Patrick
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JUN 27, 04:31 PM
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Electrical is not one of my strengths.  1.4 ohms seems a little high, although I don't know if that's enough to cause a problem.
For the couple of minutes it would take... sure, try another switch.
With the fan "never" coming on, are you absolutely sure you've gotten the engine hot enough to actually trigger the switch? The factory switch won't turn the fan on until 235°... and you can't go by the temperature gauge!
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theogre
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JUN 27, 04:35 PM
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A switch Close should be 0Ω but iffy meter or leads can make that lie. More so w/ cheap meters.
A switch Open should be ∞ Ω often OL on dig meters
The switch Plug on the car can Test good but not making contact on the switch.
Not sure if or how the plug is made for taking apart if can do that.------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
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Aaron.Russell
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JUN 27, 05:00 PM
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| quote | Originally posted by Patrick:
Electrical is not one of my strengths. 1.4 ohms seems a little high, although I don't know if that's enough to cause a problem.
For the couple of minutes it would take... sure, try another switch.
With the fan "never" coming on, are you absolutely sure you've gotten the engine hot enough to actually trigger the switch? The factory switch won't turn the fan on until 235°... and you can't go by the temperature gauge! |
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Same reading with another switch.
Unfortunately I am not 100% sure if I have actually gotten to the correct temp.
Like I mentioned I think the gauge is right, or at least kinda close. That purely a hunch though. It's of course sketchy watching the car climb well into the red.
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