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radiator fan switch by sledcaddie
Started on: 04-29-2021 01:24 PM
Replies: 17 (208 views)
Last post by: sledcaddie on 05-06-2021 08:25 PM
sledcaddie
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Report this Post04-29-2021 01:24 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
1988 Fiero GT, 2.8L, 5 speed, 12K mileage. Even when starting engine cold, the radiator fan runs, and continues to run. (No, the A/C isn't on.) Doesn't Rodney offer fan switches with different temperatures? I believe that OEM switch is set to turn on fan at 210 degrees. Most Fiero owners believe this to be too high? What temperature switches do most of you run? What is the optimal engine operating temperature? Thanks for all who input.
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Patrick
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Report this Post04-29-2021 01:42 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
 
quote
Originally posted by sledcaddie:

I believe that OEM switch is set to turn on fan at 210 degrees.


The factory fan switch turns on at 235°F.

I've found that Rodney's 210° on and 200° off fan switch works great.

If your fan is on all the time, the wiring has probably been hacked, and the fan circuit is being grounded continuously.
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Report this Post04-29-2021 02:31 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
Or the fan relay is stuck in the 'ON' position.
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sledcaddie
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Report this Post04-29-2021 06:03 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
So, where is the fan relay?

Hmmm, as far as the wiring being hacked; this car has an alarm system installed.

Is there a way to check the fan switch with a multimeter to see if it is reading properly? I don't want to replace it if not needed.
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fierofool
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Report this Post04-29-2021 06:53 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes, there is a way to check the fan switch for accuracy. Remove it and use this chart and a multimeter.
http://www.gafiero.org/bbs/...=641.msg4644#msg4644
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sledcaddie
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Report this Post04-30-2021 01:48 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
Replaced the relay, and it still runs. I'm thinking that if the fan switch that is screwed into the block was bad, the fan would never come on? I'll get a new switch from Rodney. I was going to flush the cooking system anyway.

I'm leery about the possibility that the wiring was 'hacked' somehow when the previous owner installed a security alarm. That me be my next option, is to trace the wiring from the alarm to see what was tapped into.
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Patrick
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Report this Post04-30-2021 03:25 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
 
quote
Originally posted by sledcaddie:

I was going to flush the cooking system anyway.


Running a little hot?

 
quote
Originally posted by sledcaddie:

I'm thinking that if the fan switch that is screwed into the block was bad, the fan would never come on? ...my next option, is to trace the wiring from the alarm to see what was tapped into.


Have you tried simply disconnecting the one wire that goes to the fan switch? If the fan still runs, then the switch is probably okay (although it wouldn't hurt to use Rodney's switch once this issue is resolved).

The wiring "hack" I was referring to would have nothing to do with the alarm system. It was a pretty common modification mentioned here many times over the years to ground one of the wires from the fan relay (I don't recall which one) and to put a on/off switch in the circuit for manual control of the fan. It's possible your fan circuit has been grounded with no switch wired in.
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sledcaddie
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Report this Post04-30-2021 04:31 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
No, Patrick, it is not running hot. On the contrary, with the fan running all the time, it barely warms up. I was just going to flush the system as part of maintenance before the driving season.

When looking at the relay, in front of the headlight, it doesn't appear that any modifications have been done, like what you suggested with an auxiliary switch. I will try just pulling the wire off of the fan switch, and see if the fan shuts off. Regardless, I ordered the 200/210 switch from Rodney. I had previously done that on my 85 SE.
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Patrick
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Report this Post04-30-2021 04:56 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
 
quote
Originally posted by Patrick:

Running a little hot?


 
quote
Originally posted by sledcaddie:

No, Patrick, it is not running hot. On the contrary...


Umm... I think you missed your typo that I had highlighted.

 
quote
Originally posted by sledcaddie:

I was going to flush the cooking system anyway.


Most "cooking" systems get rather hot.

 
quote
Originally posted by sledcaddie:

...with the fan running all the time, it barely warms up.


If your engine is not warming up properly... the thermostat has probably been removed or it's stuck open (or it's been replaced with a lower temperature unit). The fan running continuously would make no difference to the warm up period if the factory 195° thermostat was installed and functional.

[This message has been edited by Patrick (edited 04-30-2021).]

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sledcaddie
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Report this Post05-02-2021 06:32 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks, Patrick. I'll check to see if the thermostat is there.

Yeah, the 'cooking' system should have been the COOLING system. Good catch.

[This message has been edited by sledcaddie (edited 05-02-2021).]

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sledcaddie
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Report this Post05-04-2021 10:19 AM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

If your engine is not warming up properly... the thermostat has probably been removed or it's stuck open (or it's been replaced with a lower temperature unit). The fan running continuously would make no difference to the warm up period if the factory 195° thermostat was installed and functional.



Well, the thermostat is there, and it's closed. My next step is to disconnect the fan switch wire to see if the radiator fan stops.

Another thing might be a bad sending unit for the temp gauge. The gauge flips wide open when you turn the key, then goes back to cold. After driving awhile, the heater blows hot air. So, maybe it just 'appears' to not be warming up (on the gauge), but actually is warming up.

If I replace the radiator fan switch and the temp gauge sensor, do you use teflon thread tape, or not? I've read that the threads must ground to the block, so no tape?

Diagnosing a Fiero. Always a fun challenge. It really helps having this forum to learn from!
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fierofool
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Report this Post05-04-2021 04:25 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
The gauge sending unit is in the trunkside head near the coil. Be sure someone hasn't been duped into converting to the 'new style' sensor with the oval head. It should be round with a slit in the side of the plastic head.

No teflon tape required on either temp or fan switch. They do ground through the threads. The coolant temperature sensor underneath the thermostat housing neck can be wrapped with teflon, though. That sensor is for the ECM to adjust air fuel mixture.

[This message has been edited by fierofool (edited 05-04-2021).]

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Report this Post05-04-2021 09:10 PM Click Here to See the Profile for DukeHogSend a Private Message to DukeHogEdit/Delete MessageReply w/QuoteDirect Link to This Post
The previous owner of one of my cars put a jumper wire into a relay that is under the trunk carpet near the blower motor for the coil/alternator. I know that it made the coil blower motor run continuously but I believe that it also made the radiator fan run. I can't remember for certain. It may be something to check if you can't find the problem elsewhere.

[This message has been edited by DukeHog (edited 05-04-2021).]

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sledcaddie
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Report this Post05-05-2021 09:37 AM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
I disconnected the wires to the radiator fan switch, but the fan continued to run.

I didn't see any extra wiring, like a 'jumper' on the relay, in front of the left side headlight. I replaced it with a new one earlier. As an 88 does not have the rear blowers for the distributor/coil, there would be no relay in the trunk area.

I'll try to see if any wiring at the radiator fan has been tampered with.

I'm running out of options. Fiero issues are sometimes very frustrating!

[This message has been edited by sledcaddie (edited 05-05-2021).]

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sledcaddie
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Report this Post05-06-2021 06:16 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool:


No teflon tape required on either temp or fan switch. They do ground through the threads.



I just received a new, lower temperature, fan switch from Rodney Dickman. The instruction sheet states that you should use Teflon tape on the threads. Which is it?
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Patrick
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Report this Post05-06-2021 07:19 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
 
quote
Originally posted by sledcaddie:

The instruction sheet states that you should use Teflon tape on the threads. Which is it?


This isn't rocket science. I do two or three wraps of Teflon tape. It's thin enough that the high points of the fan switch thread easily cut through the tape and ground the unit to the engine.

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Report this Post05-06-2021 07:40 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
You need something on tapered pipe threads.

Often sensors come with pre-applied sealant in the package; in those instances, you can apply nothing. The pre-applied sealant is only good for the first time you screw the sensor in.

If the sensor is dirty/used, wirebrush the threads clean. If new, you can skip this step.

Then, you can apply Teflon tape or Teflon paste, and install the sensor.
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sledcaddie
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Report this Post05-06-2021 08:25 PM Click Here to See the Profile for sledcaddieSend a Private Message to sledcaddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
WELL!.... As a typical last resort, I turned to the handy-dandy GM service manual. In section 8A-31-6, it gives a trouble-shooting process for when the fan runs continuously. A possible culprit could be the A/C high pressure control switch. As I had the A/C converted to the newer freon last year, this might be it. It also goes on to say which colored wire might be shorted to ground, causing the fan to run. It is always personally gratifying when I can correctly diagnose the "gremlins" that infect our favorite cars. I hope to complete this process this weekend.

The reason this is taking me so long is because my Fieros are stored in the spare garages at my brother's house, which is a few miles away.
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