1986 Chevrolet Celibity

I have a black, 4 door, 1986 Chervolet Celibity. It is in mint
condition (also still has the orginial upholstery)exceptit got a tiny
power steering leak which I had to add about a tablespoon of p.s.
fluid about once a week. I was told to buy a Rack and Pinion (Cost me
$93 counting the tax and core charge. I took it to a well known
mechanic and he fixed it. He also said I had a small leak in the
radiator so I bought a radiator also. Everything else looked pretty
good. Except he, me, and a few other friends, couldn't find it in any
book why the fan runs constantly. Most of the books we found had 1985
and 1987 Chevrolets listed. Do I have a "one of a kind" auto. :-) The
mechanic said I didn't need any coolant either. I thought all cars
needed coolant. (Yes, I am a woman. :-)Any ideas?

In article >,
Jan > wrote:
>I have a black, 4 door, 1986 Chervolet Celibity. It is in mint
>condition (also still has the orginial upholstery)exceptit got a tiny
>power steering leak which I had to add about a tablespoon of p.s.
>fluid about once a week. I was told to buy a Rack and Pinion (Cost me
>$93 counting the tax and core charge. I took it to a well known
>mechanic and he fixed it. He also said I had a small leak in the
>radiator so I bought a radiator also. Everything else looked pretty
>good. Except he, me, and a few other friends, couldn't find it in any
>book why the fan runs constantly. Most of the books we found had 1985
>and 1987 Chevrolets listed. Do I have a "one of a kind" auto. :-) The
>mechanic said I didn't need any coolant either. I thought all cars
>needed coolant. (Yes, I am a woman. :-)Any ideas?

If the car is cold, hasn't been driven in a day or so, and you turn it
on, does the fan start up immediately?

If this is the case, you KNOW it's not because the thing is overheating,
it has to be because of a sensor.

In '86, the fan was probably controlled directly by a temperature-control
switch, rather than by the engine computer. Follow the wires of the fan
out and see if any of them are connected to a thing that is bolted into
the engine or screwed into the engine. If so, measure that thing with
an ohmmeter and make sure it is an open when it's cold, instead of a short.
If it's a short even when it's cold, take it out and take it to your
local auto parts store and get a replacement.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Jun 30, 1:21*pm, (Scott Dorsey) wrote:

>
> If this is the case, you KNOW it's not because the thing is overheating,
> it has to be because of a sensor.

> --scott
>
> --
> "C'est un Nagra. *C'est suisse, et tres, tres precis."

Someone could have "jumped it out" to make it run all thew time!

Scott Dorsey wrote:
> it has to be because of a sensor.
>
> In '86, the fan was probably controlled directly by a temperature-control
> switch, rather than by the engine computer. Follow the wires of the fan
> out and see if any of them are connected to a thing that is bolted into
> the engine or screwed into the engine. If so, measure that thing with
> an ohmmeter and make sure it is an open when it's cold, instead of a short.
> If it's a short even when it's cold, take it out and take it to your
> local auto parts store and get a replacement.
> --scott
>

not necessarily. Friend had an 85 Cavalier that the fan ran constantly.
Sending unit was fine. Step 2 was replace the computer, so he just
wired up a manual switch. I believe the wife's 90 Beretta and my old 84
Fiero were the same way.

Definitely start with the sensor tho.

Ray

[Good troubleshooting logic]

A possibly relevant Technical Service Bulletin came out partway
through that model year:
> 86203 DEC 86 Coolant Fan - Runs Whenever Ignition Switch is in Run

That's about all I know about it without dropping some money on
alldatadiy.com or https://www.acdelcotds.com/acdelco/action/home but
it might be worth looking into.

BTW, the fan always running (as long as it eventually goes off --
there is also a TSB for
902396B MAY 90 Cooling Fan - Runs Battery Dead ) is sure
preferable to the fan's *not* running when it needs to. But I think
any cooling-system bizarreness should be sorted out and repaired, if
you like the car and mean to keep it.

Cheers,
--Joe

PS. When working under the hood, keep in mind that these electrical
fans can come on without warning even when the engine is off...

Scott Dorsey wrote:
> In article >,
> Jan > wrote:
>
>> I have a black, 4 door, 1986 Chervolet Celibity. It is in mint
>> condition (also still has the orginial upholstery)exceptit got a tiny
>> power steering leak which I had to add about a tablespoon of p.s.
>> fluid about once a week. I was told to buy a Rack and Pinion (Cost me
>> $93 counting the tax and core charge. I took it to a well known
>> mechanic and he fixed it. He also said I had a small leak in the
>> radiator so I bought a radiator also. Everything else looked pretty
>> good. Except he, me, and a few other friends, couldn't find it in any
>> book why the fan runs constantly. Most of the books we found had 1985
>> and 1987 Chevrolets listed. Do I have a "one of a kind" auto. :-) The
>> mechanic said I didn't need any coolant either. I thought all cars
>> needed coolant. (Yes, I am a woman. :-)Any ideas?
>>
>
> If the car is cold, hasn't been driven in a day or so, and you turn it
> on, does the fan start up immediately?
>
> If this is the case, you KNOW it's not because the thing is overheating,
> it has to be because of a sensor.
>
>

Correct.

> In '86, the fan was probably controlled directly by a temperature-control
> switch, rather than by the engine computer.

It is controlled by a coolant temp switch input to the fan relay (closed
at 230*F); this circuit is also paralleled to a relay output that
requires A/C clutch command (depends on engine option: V5 runs all the
time and the DA6 cycles) and ECM approval before closing the fan relay.

> Follow the wires of the fan
> out and see if any of them are connected to a thing that is bolted into
> the engine or screwed into the engine.

That won't yield a useful result. No engine mounted switch is going to
handle 20+ amps on any vehicle I've seen. Motors of this size always go
through a relay, and the routing of the wires will not be easy to follow
what with the masses of enclosed harness and hidden relay panel backs.

> If so, measure that thing with
> an ohmmeter and make sure it is an open when it's cold, instead of a short.
> If it's a short even when it's cold, take it out and take it to your
> local auto parts store and get a replacement.
> --scott
>

Good advice. I hope the well known mechanic referenced in the above
riveting story heeds it. Then he can move on to discover the most
likely failed relay, thereby taking a logical diagnostic path towards a
solution.

BTW, I know all of this because, yes, I am a man. (note: ignorant
comment not actually intended to be taken at face value)

--
Toyota MDT in MO

Toyota MDT in MO > wrote:
>Scott Dorsey wrote:
>
>> In '86, the fan was probably controlled directly by a temperature-control
>> switch, rather than by the engine computer.
>
>It is controlled by a coolant temp switch input to the fan relay (closed
>at 230*F); this circuit is also paralleled to a relay output that
>requires A/C clutch command (depends on engine option: V5 runs all the
>time and the DA6 cycles) and ECM approval before closing the fan relay.

AAARGH! Why all this crap just for a simple fan? This is the kind of
stuff German car makers do.

So... first step is to check the fan relay.....
---scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

> >It is controlled by a coolant temp switch input to the fan relay (closed
> >at 230*F); this circuit is also paralleled to a relay output that
> >requires A/C clutch command (depends on engine option: V5 runs all the
> >time and the DA6 cycles) and ECM approval before closing the fan relay.

> AAARGH! *Why all this crap just for a simple fan? *This is the kind of
> stuff German car makers do.

Welcome to the new millennium. The only strange sounding thing about
it to me is that GM was doing it as early as '86. I just realized
that my coffeepot AND toaster both have embedded processors now.

My guess about the AC clutch, without obtaining and pondering the
schematic, is that there was a tradeoff between too much current drain
at idle (perhaps the reason the ECM gets involved) and risk of too
much lag time between actual physical overheating and fan on, since AC
adds to the engine heat load and is usually employed when the ambient
temperature is hot anyway.

A friend of mine called the late 70s and early 80s the "heart-lung
machine" era of engine controls...

--Joe

Ad absurdum per aspera wrote:
>>> It is controlled by a coolant temp switch input to the fan relay (closed
>>> at 230*F); this circuit is also paralleled to a relay output that
>>> requires A/C clutch command (depends on engine option: V5 runs all the
>>> time and the DA6 cycles) and ECM approval before closing the fan relay.
>
>> AAARGH! Why all this crap just for a simple fan? This is the kind of
>> stuff German car makers do.
>
> Welcome to the new millennium. The only strange sounding thing about
> it to me is that GM was doing it as early as '86. I just realized
> that my coffeepot AND toaster both have embedded processors now.
>
> My guess about the AC clutch, without obtaining and pondering the
> schematic, is that there was a tradeoff between too much current drain
> at idle (perhaps the reason the ECM gets involved) and risk of too
> much lag time between actual physical overheating and fan on, since AC
> adds to the engine heat load and is usually employed when the ambient
> temperature is hot anyway.
>
> A friend of mine called the late 70s and early 80s the "heart-lung
> machine" era of engine controls...
>
> --Joe

The ac needs air pulled thru the condensor. The cooling fans on most
cars run when the ac is on and the car is stopped.

Scott Dorsey wrote:
> Toyota MDT in MO > wrote:
>> Scott Dorsey wrote:
>>
>>> In '86, the fan was probably controlled directly by a temperature-control
>>> switch, rather than by the engine computer.
>> It is controlled by a coolant temp switch input to the fan relay (closed
>> at 230*F); this circuit is also paralleled to a relay output that
>> requires A/C clutch command (depends on engine option: V5 runs all the
>> time and the DA6 cycles) and ECM approval before closing the fan relay.
>
> AAARGH! Why all this crap just for a simple fan? This is the kind of
> stuff German car makers do.
>
> So... first step is to check the fan relay.....
> ---scott

No they don't, or at least didn't start doing it until much later. All
my German cars (well, not sure about the '02 GTI) used a simple
thermoswitch in the radiator, and a relay (also tied into the A/C if car
has it.) That's it.

People accuse German cars of being overly complex, and in some cases
that is justified, but it's a really recent phenomenon. Overengineered,
yes, but overly complex...

Now I would say "that's the kind of thing I'd expect from a Japanese car" :P

nate

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