1984 Cooling fan problem
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 48
1984 Cooling fan problem
My cooling fan shut off. So I checked the wire feeding power to the fan motor relay. It was dead. I changed the fuse. It blew as soon as I put it on.
I ran a new fused wire from the fuse box to relay. The fuse blew as soon as the fan tried to go on. So I took another relaym it was on the fire wall next to the washer motor. I plugged the connector in and the fan did not go on. So now I have bypassed the fuse and the fan turns on.
So any ideas on what is wrong. Oh I had a nother fan and plugged it in. And the fuse blew.
Relay?
When your fan operates and the car drops below the temperature to engage the fan does the fan go off. Oh once the fan is on its on until you shut the car?
Last question does anyone know what the other relay operates?
I ran a new fused wire from the fuse box to relay. The fuse blew as soon as the fan tried to go on. So I took another relaym it was on the fire wall next to the washer motor. I plugged the connector in and the fan did not go on. So now I have bypassed the fuse and the fan turns on.
So any ideas on what is wrong. Oh I had a nother fan and plugged it in. And the fuse blew.
Relay?
When your fan operates and the car drops below the temperature to engage the fan does the fan go off. Oh once the fan is on its on until you shut the car?
Last question does anyone know what the other relay operates?
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
It does sound like the relay is bad.
I don't know how the '84 fan works. I'm pretty sure it uses the temperature switch in the passenger side head (it changed in later years so that's why I'm not sure). The fan should go on when the coolant is hot and go off when it cools down.
By "other relay" I assume you mean the one on the firewall that you tried. That's probably the fuel pump relay. Your description is too vague to be sure.
I don't know how the '84 fan works. I'm pretty sure it uses the temperature switch in the passenger side head (it changed in later years so that's why I'm not sure). The fan should go on when the coolant is hot and go off when it cools down.
By "other relay" I assume you mean the one on the firewall that you tried. That's probably the fuel pump relay. Your description is too vague to be sure.
Instructor
Joined: Aug 2013
Posts: 156
Likes: 1
From: Springfield MA
first thing, make sure all the wiring is sound, nothing loose / broken. next, make sure fan turns freely by hand. When you bypass the fuse, do you also bypass the relay? Did the second fan (for testing) have the same current/power rating as the one in the car?
if you run a fused wire directly to the fan and it works, it's either the relay or a short in the wiring. If the fuse still blows, it's the fan. it might also be interesting to hot wire the fan so it runs, then check the current on the wire and compare that to the fuse rating or the fan motor nameplate rating.
if you run a fused wire directly to the fan and it works, it's either the relay or a short in the wiring. If the fuse still blows, it's the fan. it might also be interesting to hot wire the fan so it runs, then check the current on the wire and compare that to the fuse rating or the fan motor nameplate rating.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 48
cooling fan
first thing, make sure all the wiring is sound, nothing loose / broken. next, make sure fan turns freely by hand. When you bypass the fuse, do you also bypass the relay? Did the second fan (for testing) have the same current/power rating as the one in the car?
if you run a fused wire directly to the fan and it works, it's either the relay or a short in the wiring. If the fuse still blows, it's the fan. it might also be interesting to hot wire the fan so it runs, then check the current on the wire and compare that to the fuse rating or the fan motor nameplate rating.
if you run a fused wire directly to the fan and it works, it's either the relay or a short in the wiring. If the fuse still blows, it's the fan. it might also be interesting to hot wire the fan so it runs, then check the current on the wire and compare that to the fuse rating or the fan motor nameplate rating.
The ciruit is a simplw one that does not include the ECM. But I still thought that the fan should go on and off to maintain temperature rater than just cool the car,
I have a 185 thermostat and a 205 switch in the car. But once the fan comes on it lowers the trmperature so low that the idle goes up to warm the car.
Thank you for the great post
Instructor
Joined: Aug 2013
Posts: 156
Likes: 1
From: Springfield MA
Do you have an ALDL? It'd be a rectangular plug under the dash to the right of the steering column. On my 85, i can short out two pins (a to b maybe?) turn the car on, and the fan will run. If the fan won't maintain, that almost sounds like a sticky switch. a bad switch could also cause a short and blow your fuse.
I was never a big fan of flow charts. It sounds like you have the schematic, which is good. Basically what i'd do, is look at the print, then jump out each device in the circuit one at a time. when the fan runs, and the fuse doesn't blow, what ever device is jumped out at that time is your problem.
I was never a big fan of flow charts. It sounds like you have the schematic, which is good. Basically what i'd do, is look at the print, then jump out each device in the circuit one at a time. when the fan runs, and the fuse doesn't blow, what ever device is jumped out at that time is your problem.
Thread Starter
Drifting
Joined: Feb 2013
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This morning I took the relay out of circuit and blew the fuse as soon as I connected the either of the two fans I have. The fan switch which goes into the block is only about one month maybe two months old. I did over heat the car once but the fan worked after the over heat.
How do I try the circuit without the switch. Just disconnnect the switch and hot wire the fan?
I ported the manifold which worked really great. I am wondering if I did not pinch a wire and it is bare and shorting some where. Oh and how do I test the amps it is pulling. I tried putting my voltmeter pins negative and positive in the fuse slot but did not get the fan to to run or a reading.
Thank you all
How do I try the circuit without the switch. Just disconnnect the switch and hot wire the fan?
I ported the manifold which worked really great. I am wondering if I did not pinch a wire and it is bare and shorting some where. Oh and how do I test the amps it is pulling. I tried putting my voltmeter pins negative and positive in the fuse slot but did not get the fan to to run or a reading.
Thank you all
Safety Car
Joined: Jan 2004
Posts: 3,556
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Touch the wire at the fan switch on the head, the relay should operate
and supply power to the fan motor (if the fuse does not blow )
You don't.
As the most likely cause of your instant fuse blow is a direct connection to ground somewhere ,with the meter on the Ohm scale you test each part of the fan power circuit
The fan switch is on the control circuit , not the power circuit so that is not your problem.
and supply power to the fan motor (if the fuse does not blow )
You don't.
As the most likely cause of your instant fuse blow is a direct connection to ground somewhere ,with the meter on the Ohm scale you test each part of the fan power circuit
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Instructor
Joined: Aug 2013
Posts: 156
Likes: 1
From: Springfield MA
The fan switch is on the control circuit , not the power circuit so that is not your problem.
I agree, though, that it's probably a wire touching off somewhere.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
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I ordered a relay. So I figure I will put it in on Wednesday when it is delivered. But I will have to look for a pinched wire. Would the switch wire blow the fuse? I do not think so.
Thread Starter
Drifting
Joined: Feb 2013
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Fan switch
The 3A fuse in the fuse box. Blows as soon as I put it in. I just moved the car. The engine was at 100 degrees but the fan still came on. It seems to me once the fan goes on unless I let the car sit for a very long time the fan comes on.
I ordered a relay. So I figure I will put it in on Wednesday when it is delivered. But I will have to look for a pinched wire. Would the switch wire blow the fuse? I do not think so.
I ordered a relay. So I figure I will put it in on Wednesday when it is delivered. But I will have to look for a pinched wire. Would the switch wire blow the fuse? I do not think so.
And thanks again for the diagrams and input.
Melting Slicks
Joined: Dec 2009
Posts: 2,241
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Corvette Central sells a switch that goes on at 200 and off at 185. Has any body used this switch. Does it work? Its 39.95 is there a cheaper carrier. Actually I was looking for something that would go on at 215 and off at 195/200. Any helpmout there.
And thanks again for the diagrams and input.
And thanks again for the diagrams and input.
Last edited by ex-x-fire; Sep 22, 2013 at 09:22 PM.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
As you are blowing the fuse in the fuse panel you have a problem with the fan CONTROL circuit ;
not the fan POWER circuit which is protected by the fusible link down by the starter motor.
Pull the fuse , put your probes on a ground point and the blue wire at the relay connector and see what the Ohm reading is ???
FWIW.
If you had a ground short after the fan relay, the fan would run full time as soon as you turn the key on
Safety Car
Joined: Jan 2004
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If it was after the relay it would just operate the relay the same as the fan switch ,it should not blow the fuse
Is no different than taking the wire off the switch and grounding it to the head which I previously mentioned as the std test for fan relay / fan switch checking
The fan switch is just a "short" , it puts the power to ground at a certain temp to operate the fan relay
However there could be a short inside the relay before the windings that operate the relay.
Instructor
Joined: Aug 2013
Posts: 156
Likes: 1
From: Springfield MA
The fan switch is just a "short" , it puts the power to ground at a certain temp to operate the fan relay
However there could be a short inside the relay before the windings that operate the relay.
However there could be a short inside the relay before the windings that operate the relay.
Thread Starter
Drifting
Joined: Feb 2013
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[QUOTE=RePete;1584988178]Right. If the circuit is grounded in the relay or before it, there will be no load on the circuit (short circuit), and all available current will flow directly to ground, blowing the fuse. it'd be like sticking a fork in a light socket.[/QUOTE
so I disconnected the relay and put a fuse in the line 3A turned on the key and blew the fuse before the fan turned once.
so I disconnected the relay and put a fuse in the line 3A turned on the key and blew the fuse before the fan turned once.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
So you just proved what has already been said; you have a short somewhere between the fuse and the relay
Your problem is not the fan motor
If the relay is disconnected the fan won't turn ever