Fans won't turn on.

T

Turbo6Smackdown

Well-Known Member
Joined
Dec 31, 2005
Ok, got the car up to temp and grounded the wire coming off the fan turn on switch on the manifold and the fans turned on, so I presumed it was the switch. Busted my ass to put a new one in and nothing. The fans are as dead as they were before. So I read that it may be the relays or the fuseable link by the starter. But aren't the relays down stream of the fan turn on switch? I mean that, if the wire coming off of the turn on switch when grounded, spins the fans, then that means that the relays are working too, right? And could the fuseable link off of the starter be open but the fans still turn on if I ground that turn on switch wire? Please help.
And keep it simple too, I have NO clue when it comes to electrical yet. Haven't taken that course as of yet. I don't even know what a ground is, or what it means.
 
Edit: I was just sitting here thinking about what I just posted. It's electricity. It shouldn't matter if the link or the relays are up or downstream of the wire that comes off of the turn on switch; if I ground that wire and the fans come on, the circuits complete-the relays or link can't be bad; the fans turned on. I'm now more lost after I replaced that switch than before...
 
The turn on sw you grounded is not likely to work at temps less than about 230*. So, if you bypassed it, and fans worked, then didn't could likely be the sw wasn't bad to begin with.
 
Also, low speed signal comes from the ecm, high speed comes from the sender switch on the manifold.

Sounds like you may have lost signal from the ecm. Using a scan tool, verify the ecm is trying to turn the fan on. Then check the signal on the fan circuit. D2 on the ecm (Drk/grn wire). Check it at the ecm, then at the relay. O and I'm pretty sure the ecm is providing the ground not power. So test accordingly.

Rick
 
Chuck Leeper said:
The turn on sw you grounded is not likely to work at temps less than about 230*. So, if you bypassed it, and fans worked, then didn't could likely be the sw wasn't bad to begin with.
Click to expand...
Yea, I read that after I posted... Madder than hell I went thru that trouble lol. I realized afterwards. Gotta slow down a bit.
Ok, next question. At idle, when you're out driving, and the fans kick on, which speed is it? And besides the ten minutes after you shut your car off when it's super hot, when do the high speed fans kick on?
 
My fan wouldn't come on when I bought my car. I checked the fan wire to the starter and found it hanging.
 
The fan runs on low speed until 220 degrees when the overtemp sensor switches it to hi mode. It does not matter if the car is on or off. The low fan should turn on with the a/c on or when the coolant is 170/180 degrees.
 
Shawn N said:
The fan runs on low speed until 220 degrees when the overtemp sensor switches it to hi mode. It does not matter if the car is on or off. The low fan should turn on with the a/c on or when the coolant is 170/180 degrees.
Click to expand...


High temp OR A/C will kick the high speed mode on.
 
The A/C switch can run both high and low speed depending upon pressures in the high side port.

ECM runs low speed, water switch is around 220 degrees and high speed trigger.
 
Ah I see. I don't think my ac blows cold any more. Is that affecting anything though? Should I get it recharged?
 
No high side pressure means the fans won't trigger when the slider is moved to A/C and of course the compressor won't come on and it won't get cold.....

Fixing the A/C isn't the best way to make the fans work, the ECM should be doing it along with the high temp. switch.
 
Got 'er workin'. Did the test for the simple minded off the fan write up from vortex buicks, and sure enough, the high speed worked but not the low speed. So I switched them and good to go. But I still want this thing working the way it did from the factory. Though, I can't find my delay relay. Anyone have a picture of the wire that plug into their delay relay for me? :)
 
This is what's left. Am I to assume these two plugs left just hanging out there used to plug in to my delay relay?
 

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If the high speed fan works and the low speed doesn't (assuming you checked the relay and wiring) then the low speed resistor on the fan shroud is open.

Quick tip to check relays: Gray weatherpack connector on the switch mounted on the AC pressure line, key on, umplug it and jump A and C first, B and C next. Fan should run when either terminals are jumped.

Racers trick: Tie all wires at the resistor together and eliminate the resistor.

Best Advice: Delay relay is useless and should be removed. It creates more problems than it solves.
 
Ahhh ok. Delete the delay relay. Roger. Got it. I also called your shop to ask about jumping the resistor for high speed operation all the time, and the other guy there said he thinks it would be ok. Good to have confirmation from the man himself. Thanks! (now, how do I delete the resistor without burning the car down...)
 
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