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Fan Stays on by Spadesluck
Started on: 05-03-2019 06:48 PM
Replies: 18 (209 views)
Last post by: hobbywrench on 05-15-2019 11:02 AM
Spadesluck
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Report this Post05-03-2019 06:48 PM Click Here to See the Profile for SpadesluckSend a Private Message to SpadesluckEdit/Delete MessageReply w/QuoteDirect Link to This Post

I have an 87 GT. Wasn't until recently the fan just stays on with the key in the on position. Things I have checked:

Relay...tested it with a power supply and it does is job in clicking on and off
Sensor....I disconnected the sensor and the fan stays on

I can only assume that I have a grounded wire some where then? Is there any fuse associated with the fan electronics? Ideas?

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Patrick
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Report this Post05-03-2019 09:41 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post


Turn off the A/C.

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Spadesluck
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Report this Post05-03-2019 11:47 PM Click Here to See the Profile for SpadesluckSend a Private Message to SpadesluckEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Patrick:


Turn off the A/C.


It is off.

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cliffw
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Report this Post05-04-2019 02:56 AM Click Here to See the Profile for cliffwClick Here to Email cliffwSend a Private Message to cliffwEdit/Delete MessageReply w/QuoteDirect Link to This Post

There is a reason I offer no help here in Tech. I know nothing compared to the many tech gurus.

There has to be a fuse but, what would that matter ? If it's blown, the fan won't work. Testing purposes ?

I have the opposite problem. Mine won't come on, unless the A/C is on. Where is the relay ? The sensor ?

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Spadesluck
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Report this Post05-04-2019 03:02 AM Click Here to See the Profile for SpadesluckSend a Private Message to SpadesluckEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by cliffw:

There is a reason I offer no help here in Tech. I know nothing compared to the many tech gurus.

There has to be a fuse but, what would that matter ? If it's blown, the fan won't work. Testing purposes ?

I have the opposite problem. Mine won't come on, unless the A/C is on. Where is the relay ? The sensor ?


Relay is in front of the driver side headlight. Sensor is a one wire plug next to the thermostat on the motor. Yours sounds like a fan sensor is bad.

I asked for a fuse to make sure I do not have a short in there.

[This message has been edited by Spadesluck (edited 05-04-2019).]

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Blacktree
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Report this Post05-04-2019 10:25 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post

To Spadesluck, I'm assuming you tested the relay with the engine off? If the engine is on, and the fan is running, the relay shouldn't be clicking on and off (it should be constantly on). So I'm assuming something is holding the relay on whenever the ignition is hot. If that's the case, then you probably have a short to ground in the green&white wire that activates the relay. That wire runs to a lot of places (like the fan switch, the A/C compressor, and the HVAC panel). But you could start by unplugging those things one by one, and see if anything changes.

To CliffW, I'm guessing a bad relay. Like mentioned above, it's under the driver side headlight. You can test the relay using a paperclip, or a short piece of wire, as a jumper. With the ignition on, back-probe the green&white wire, and touch the other end of your jumper to a chassis ground. The relay should click (and the fan should come on). If it doesn't, the relay is probably toast. If it does, then the fan switch is probably toast. If you end up replacing the fan switch, I would suggest getting a 210°F fan switch from Rodney Dickman. ---> http://rodneydickman.com/ca...th=22&products_id=88

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Spadesluck
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Report this Post05-04-2019 03:17 PM Click Here to See the Profile for SpadesluckSend a Private Message to SpadesluckEdit/Delete MessageReply w/QuoteDirect Link to This Post

Found my problem. One of the pressure switches on my AC Compressor is triggering the fan on all the time with the key in run. I check this by unplugging all the sensors one at a time and leaving them unplugged. Figured I would pass this along.

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Blacktree
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Report this Post05-04-2019 04:14 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post

The good news is, even with the wire unplugged from the A/C compressor, the HVAC panel will still turn on the fan. However, replacing the fan switch on the compressor will require evacuating the refrigerant.

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Spadesluck
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Report this Post05-04-2019 04:34 PM Click Here to See the Profile for SpadesluckSend a Private Message to SpadesluckEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Blacktree:

The good news is, even with the wire unplugged from the A/C compressor, the HVAC panel will still turn on the fan. However, replacing the fan switch on the compressor will require evacuating the refrigerant.


Which is why I am just going to leave it alone right now.

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cliffw
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Report this Post05-04-2019 07:57 PM Click Here to See the Profile for cliffwClick Here to Email cliffwSend a Private Message to cliffwEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Spadesluck:
Relay is in front of the driver side headlight. Sensor is a one wire plug next to the thermostat on the motor. Yours sounds like a fan sensor is bad.


Thank you. Thank you.

 
quote
Originally posted by Spadesluck:
I asked for a fuse to make sure I do not have a short in there.


In where ? Am I missing something ?
12v go into the fuse and comes out the other side. A short would blow the fuse. Then it would't run at all.
Am I missing something ?

Do you have a test light ? An ohm meter ? You can make a test light from a Fiero side marker lamp.

[/QUOTE]

You don't have a short. You have something energizing the fan.

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cliffw
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Report this Post05-04-2019 08:01 PM Click Here to See the Profile for cliffwClick Here to Email cliffwSend a Private Message to cliffwEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Blacktree:
To CliffW, I'm guessing a bad relay. Like mentioned above, it's under the driver side headlight. You can test the relay using a paperclip, or a short piece of wire, as a jumper. With the ignition on, back-probe the green&white wire, and touch the other end of your jumper to a chassis ground. The relay should click (and the fan should come on). If it doesn't, the relay is probably toast. If it does, then the fan switch is probably toast. If you end up replacing the fan switch, I would suggest getting a 210°F fan switch from Rodney Dickman. ---> http://rodneydickman.com/ca...th=22&products_id=88


Thank you. Thank you.

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Spadesluck
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Report this Post05-05-2019 01:28 AM Click Here to See the Profile for SpadesluckSend a Private Message to SpadesluckEdit/Delete MessageReply w/QuoteDirect Link to This Post

Cliff, I found my problem as I stated above. Now to answer your question about a fuse and short. Either would not matter because they both would be supplying 12v. Sorry to confuse. I was really looking for the path of the fan power.

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cliffw
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Report this Post05-05-2019 09:51 AM Click Here to See the Profile for cliffwClick Here to Email cliffwSend a Private Message to cliffwEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Spadesluck:
Now to answer your question about a fuse and short. Either would not matter because they both would be supplying 12v. Sorry to confuse. I was really looking for the path of the fan power.


Congrats to (almost) solving your problem. I never would have thought to look there.

No need to be sorry about confusing me. I am good at it all by myself, .
I am still confused. More like ignorant (not enough knowledge). I am trying to learn.

You were looking for a fan fuse yet you are getting unwanted power from the A/C. Does the A/C send a fan signal back to the fan fuse, or bypass it and go directly to the fan ?

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olejoedad
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Report this Post05-05-2019 09:58 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post

The fan is turned on by grounding the coil on the fan relay. The coil is always supplied power with key on, it's just waiting to be grounded to activate the relay.
The devices that can supply the ground are the HVAC control, the A/C pressure switch, and the FAN temp sensor.
In pre-88 V-6 cars, the trunk mounted cooling fan relay is also triggered on by the same grounding devices.

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cliffw
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Report this Post05-05-2019 12:07 PM Click Here to See the Profile for cliffwClick Here to Email cliffwSend a Private Message to cliffwEdit/Delete MessageReply w/QuoteDirect Link to This Post

Thank you.

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Report this Post05-05-2019 02:43 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

Rad Fan Motor has No Fuse. Is wired directly to the "battery box" in back via Fuse Link A.
Efan fuse only affects fan switches etc that turns on the relay.
See my Cave, Rad Fan

Many people have installed fan switch or wiring the green wire to always be grounded and fan on.
So if on now, look for none OE switches installed by previous owners.

------------------
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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hobbywrench
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Report this Post05-13-2019 11:45 AM Click Here to See the Profile for hobbywrenchSend a Private Message to hobbywrenchEdit/Delete MessageReply w/QuoteDirect Link to This Post

Without trying to trace or simply write it off as the electrical gods at work. ...Just before alternator failure the fan was running constantly. Stopped after kit installed (brushes, controller module). I (of course ) should not mention this at risk of wakening the gods (or failure of the Chinese sourced module)

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olejoedad
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Report this Post05-13-2019 12:51 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by hobbywrench:

Without trying to trace or simply write it off as the electrical gods at work. ...Just before alternator failure the fan was running constantly. Stopped after kit installed (brushes, controller module). I (of course ) should not mention this at risk of wakening the gods (or failure of the Chinese sourced module)


There is no correlation between your alternator issue and the cooling fan running constantly.

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hobbywrench
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Report this Post05-15-2019 11:02 AM Click Here to See the Profile for hobbywrenchSend a Private Message to hobbywrenchEdit/Delete MessageReply w/QuoteDirect Link to This Post

Long time ago I gave up on trying to trace "crazy currents." LIke applying Kirchoff's law to the GM wiring. I'll let the gods continue to keep my fan off.

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