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Old 04-15-2012, 01:51 PM   #1
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Default '92 LeSabre Cooling Fans Always On (even with ECC Off)

The cooling fans (both) seem to be on constantly - even on the first start in the morning. Even with the Electronic climate control unit turned OFF. I've searched for related threads, and I'll try to answer the common questions first - The A/C compressor is plugged in & seems to be working fine, I can hear it kick in when I hit the A/C button (and air blows cool). As stated above, it is an Electronic climate control unit, and the fans come on even when it'* set to OFF.

They're pretty noisy, I'd guess they were on "High" (the noise level seems to dissipate after a few minutes, or maybe my ears just get used to it).
This is not a new development - I've heard a bit of a noise on cold starts since I got the car, I thought it might've been the CAI or possibly a noisy P/* pump or Alt or belt, I've had other cars do that. But today I had the hood up on the first start of the day, and when I heard the noise I figured I'd have a look and saw that both fans were running, and the engine was dead-cold.

I drove the car for a number of miles, and the fans were on when I got home (which I expected). I then let the car just sit for over an hour (with the hood up, to cool off, though it'* not hot out today and the engine wasn't overly hot), and when I started it again the fans came on immediately. I presume they must be running all the time. I know that fans aren't designed to run constantly and I'd like to fix this problem before the fan motors wear out & die on me (on the hottest day of the year, stuck in traffic, in a tunnel or on a bridge with nowhere to pull over.. yeah, I'm an optimist lol).

Fans running constantly seems to be a somewhat common problem, but all of the threads the search returned were concerning other makes & models..

All thoughts & suggestions appreciated.. Thanks!
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Old 04-15-2012, 02:03 PM   #2
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Pull the relay and swap it with another one. Me thinks the relay is stuck closed.
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Old 04-15-2012, 03:19 PM   #3
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Quote:
Originally Posted by Mike1995 View Post
Pull the relay and swap it with another one. Me thinks the relay is stuck closed.
there was actually a TSB about this for different cars of roughly the same era... basically, the a/c compressor and fan relays engaged at the same time, causing the relays to weld into the on position.

however.... the switched portion of the relay is connected to a constant +12V circuit, so even with the ignition off the fans would run.

it sounds like the PCM is turning them on for one reason or another. if you could view sensor data, that would be helpful. i doubt any codes are getting tripped since you didn't mention it.

if i had to guess though... i'd look at replacing the coolant temp sensor first(do an ohm check if possible to verify that it'* functioning incorrectly), then possibly the PCM/PROM.
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Old 04-15-2012, 07:44 PM   #4
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Thanks for the ideas

I'll try swapping the relays, and it sounds like checking the coolant temp sensor is a good idea, too..
I have an ohmmeter, but don't know the testing procedure, is it in the Haynes manual..?
I'll have to check in there to see which relay does what anyhow lol..
I remember reading on another thread about a Module for the Electronic climate control
located under the relay box or something along those lines..
Could that module be bad as well..?
As I recall reading, the coolant temp sensor isn't all that expensive, and if I need any relays or a climate control Module, there are '91 and '92 Park Aves and a '96 LeSabre in a boneyard nearby.
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Old 04-15-2012, 07:48 PM   #5
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the test procedure SHOULD be in a haynes. basically, disconnect the sensor and measure resistance across the two terminals (yours may be a 3 teminal unit? not too familiar with 3800s). then check to see if the resistance is somewhat close to a chart for resistance vs temperature.
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Old 04-15-2012, 09:25 PM   #6
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Default FSM or experienced tech needed

The test may be in there, haven't looked for it yet..
then again it may not be, they're not a very comprehensive or detailed manual.
I found a general wiring diagram showing the fan relays, but there'* no indication of which slots the fan relays are in. I tried to figure out which was which by the color of the wires but the colors didn't match those on the generic wiring diagram.

Below is a pic of my car'* Relay Center -

Does anyone have an FSM for a '92 Buick LeSabre?
I need to know which relay is in which slot..



As you can see, from left to right, there are two relays, then two empty slots, then 4 more relays.
Does anyone know which relay is which, based on the position of the relays..?

Thanks
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Old 04-15-2012, 09:38 PM   #7
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i managed to grab and splice this... not perfect, but it should do.

http://i.imgur.com/o1vRK.png
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Old 04-16-2012, 09:06 PM   #8
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..That.. is.. AWESOME

Thank you!
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Old 04-16-2012, 10:57 PM   #9
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It was my understanding that when the PCM does not see a signal from the temp sensor, it kicks the fans on high and trips a Service Engine Soon light. There may also be a short as well.
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Old 04-16-2012, 11:00 PM   #10
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complete lack of signal will cause a SES and fans on...

however, a skewed sensor that reports just within the range of considered "not bad" will cause the fans to run without a SES.
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