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?

Reply to
Jan
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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

Reply to
Scott Dorsey

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

Reply to
twisted

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

Reply to
ray
[Good troubleshooting logic]

A possibly relevant Technical Service Bulletin came out partway through that model year:

That's about all I know about it without dropping some money on alldatadiy.com or

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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...

Reply to
Ad absurdum per aspera

Correct.

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.

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.

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)

Reply to
Toyota MDT in MO

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

Reply to
Scott Dorsey

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

Reply to
Ad absurdum per aspera

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.

Reply to
Steve Austin

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

Reply to
Nate Nagel

Toyota didn't start using ECM fan control until about 2000ish; 2002 Camry, 2003 Corolla, and 2004 Sienna are a few specific examples.

:P right back at ya!

Reply to
Toyota MDT in MO

Nate Nagel wrote in news: snipped-for-privacy@news2.newsguy.com:

Honda didn't even start using relays in their fan control until about 1992.

Prior to that it was a simple thermal switch to ground through the fan motor; as crude as it can get.

Reply to
Tegger

The guy might be well known, butif he cant diagnose a simple circuit.... Power, ground and relay trigger is all... But seriously, I diagnosed a ton of these by looking at the relay connector... when these things fail they tend to leave heat evidence at the relay connection. HTH Ben

Reply to
ben91932

HTH? You're assuming the well known mechanic knows of this thread *and* can read.

Reply to
Toyota MDT in MO

Heck, I thought *all* cars had horn relays! My '55 Stude has one, and I'm sure that it wasn't new for that year.

The nice thing about using a horn relay is then you don't have all that juice traveling up the steering column, which used to be metal back in the day (although you still have the directional signal wires...) the horn wire in the column is current-limited by the horn relay coil.

nate

Reply to
N8N

Do you know of a (for example) late 80's Honda that works as you say? I'm not aware of one.

Reply to
Toyota MDT in MO

Toyota MDT in MO wrote in news:_Uq4m.2642$ snipped-for-privacy@nlpi061.nbdc.sbc.com:

I might have been a bit too broad with my original comment.

On further investigation it looks like the no-relay arrangement was the case only with rad fans on vehicles _without_ A/C. Cars _with_ A/C always had relays to carry rad fan current.

I find numerous non-A/C Hondas from the late '80s up to 1991 with no relays for the rad fan. My 1991 Integra is one of them. The rad fan thermo- switches on those cars are not too reliable.

Reply to
Tegger

z wrote in news: snipped-for-privacy@s31g2000yqs.googlegroups.com:

If you have SRS, you have a horn relay. As far as I'm aware, only non-SRS Hondas had no horn relay. (I'm trying to be careful here so as to prevent that Toyota guy from Missouri calling me on this.)

On those non-SRS cars, I've seen surface corrosion on the little brass tab that carries current from the wiring to the slip ring prevent the horn from working fully (horn makes a sort of buzzing noise instead). Sand the tab nice and clean and things are OK again. Tends to get diagnosed as bad horns.

Reply to
Tegger

I'll be damned! I can't remember the last Honda product I saw without A/C. I checked many diagrams from the 80's before asking the question, and they all show (perhaps erroneously) two relays and two fans being employed with or without A/C. I then checked your car specifically and the diagram is correct as you describe it. What a piece of crap setup! Have you considered (or already tried) wiring in a relay? I've done that with success on the older Toyota neutral safety circuits that get gummed up inside the PRNDL switch housing and can't handle starter solenoid current anymore. Another quality omission of a $0.50 relay.

I just checked the only paper OEM EWD I still have (1990 Civic, all models) and it shows one fan, one relay on the without A/C system. The

88 Civic rollout is about as far back as I can remember anyway :-)
Reply to
Toyota MDT in MO

Toyota MDT in MO wrote in news:U0v4m.7246$ snipped-for-privacy@nlpi069.nbdc.sbc.com:

Yep.

Generally, I like Hondas, but boy they do some weird stuff sometimes.

With my car, I figure they spent so much money on that Chinese-puzzle of a rear suspension that they didn't have any money left for more relays.

Nah. I've put up with this for 18 years. I've gotten used to treating the fan switch as a consumable. It's cheap and only takes a few extra minutes at oil-change time to swap. Actually, last time it failed, it kicked the fan in way too SOON, so the fan ran as long as the coolant temp was above about 150F. Drove me nuts, I tell ya.

My '91 Civic paper manual shows relays in both cases as well, but for US only. Canada had no relay with AND without A/C.

I'm seeing the '88 Civic with no relay when not equipped with A/C...

Reply to
Tegger

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