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05-26-2014
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#1 |
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Join Date: Sep 2013
Location: akron OH
Posts: 38
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Cooling fans not turning on
So I noticed my cooling fans weren't turning on. Checked the fuse it was good. Unplugged the fan switch so now they both run full time. Does this mean the relays are bad or is there something else I need to check too?
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05-26-2014
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#2 |
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Join Date: Dec 2012
Location: NC
Posts: 1,783
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Re: Cooling fans not turning on
Here's a schematic from some NON-fan diagnostics on a '94 (never mind my notes)...
 
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05-26-2014
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#3 |
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Join Date: Dec 2012
Location: NC
Posts: 1,783
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Re: Cooling fans not turning on
Some other notes on this schematic WILL apply to your testing:
On the '90, ECM harness 'C'; socket '6', is the same as A 11, and 2nd fan 'D' 11, is substituted for harness 'A', socket 10, in the diagram. 
Last edited by Schrade; 05-26-2014 at 02:01 PM. |
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05-26-2014
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#4 | |
 
Join Date: Feb 2006
Location: San Antonio area
Posts: 1,183
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Re: Cooling fans not turning on
Quote:
It sounds like you are describing a low freon condition ...
__________________
“Buy the best example of what you want, and pay whatever it takes. That way, you cry only once.” ~ Bruce Meyer |
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05-26-2014
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#5 |
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Join Date: Sep 2013
Location: akron OH
Posts: 38
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Re: Cooling fans not turning on
I unplugged the fan switch on the a/c line located by the right wheel well. I just noticed the problem recently. They don't turn at all if I plug the switch back in.
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05-26-2014
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#6 |
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Join Date: Feb 2006
Location: San Antonio area
Posts: 1,183
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Re: Cooling fans not turning on
That's not a fan switch - it's a normally open switch that closes when the pressure in the hard line is too low for the AC system to run - it's a safety measure, and the fans will not run in that case. Do the AC control head LEDs blink? If so, the AC system is probably low on freon.
__________________
“Buy the best example of what you want, and pay whatever it takes. That way, you cry only once.” ~ Bruce Meyer |
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05-26-2014
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#7 |
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Join Date: Sep 2013
Location: akron OH
Posts: 38
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Re: Cooling fans not turning on
That would make sense. I did have to remove an a/c line to replace the lower radiator hose which would have relieved all the pressure. It has a bad condenser so I never thought to recharge the system since it'll just bleed out eventually. I'll recharge the system and see if the fans will kick on again.
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05-26-2014
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#8 |
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Join Date: Feb 2006
Location: San Antonio area
Posts: 1,183
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Re: Cooling fans not turning on
Best to leave the connector attached - with it disconnected, the AC compressor can run when AC is called for and since there is no freon in the system, you will probably trash the compressor. The fans will cycle normally when the coolant gets hot enough.
__________________
“Buy the best example of what you want, and pay whatever it takes. That way, you cry only once.” ~ Bruce Meyer |
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05-26-2014
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#9 |
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Join Date: Sep 2013
Location: akron OH
Posts: 38
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Re: Cooling fans not turning on
The fans don't cycle at all. At first I thought I had an air pocket in the cooling system and while I was bleeding it was when I realized the fans didn't kick on at all. The temp just keeps climbing and climbing.
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07-09-2014
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#10 |
Join Date: Aug 2006
Location: Fishkill, NY
Posts: 87
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Re: Cooling fans not turning on
Hi OP -
Did you ever get this resolved? I've just come back from a short but spirited trip, and I got temp gage up to 260 and the electronic gage at 261. Fans would not come on. I turned the ignition on (engine off), and connected terminals A and B on the ALDL connector... and both fans are running... so wondering why it's not coming on. Will research more. Steve |
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Linear Mode
