[fireforsin]

i know that this isn't exactly a "hot rod" type question but here goes...

i just acquired a 1986 Chevy Celebrity. the problem is the electric fan does not turn on when the car gets hot so the car over heats. i tested the fan by plugging it directly into a power source and the fan worked perfectly. i am not very knowledgeable on these computer controlled fuel injects engines and was wondering if anyone could help me out with this.

thanks,
mike

[brian0605]

Well, you need a service manual.I can't remember if I still have one. You should be able to find one at most any big box parts store. I would say that you need to find the fan relay to start with. You need to verify that it is working. If you're not sure how to check it let me know. then we'll move on from there. Brian

[poncho62]

The temp sending unit also switches the fan on and off on those, I believe.......Probably your problem.

[fireforsin]

by any chance do you guys know where these parts are. i picked up a manual but it is one of those stupid manuals that are for like 50 different vehicles. they are also no use with fixing the problem.

[UR50SLO]

You can do one of two things.....

There is two temp. sending units on your car. The one your looking for is a single wire sending unit and controlls the fan coming on. (green or green/white tracer) located on the intake around the T-Stat area.

You did not state what engine was in your car, 2.8L V6 or 2.5L 4cyl.

If you take that green or green/white tracer to ground with the key turned on the fan should run. You can ground it to the block there and the fan will only run when the key is on. (or replace sender and hook back up) or you'll need to find the relay that is located towards the front or sides of the engine bay that share's the color wires that go to the main fan and green/ green with white tracer wire. Replace the relay.

The problem is either the sensor or the relay. If you find it's the sensor and decide to replace it, it will only come on at around 210deg. If you just ground it the car will run cooler. Your choice....
Hope that helps,
Scott~

[brian0605]

UR50SLO has a pretty good handle on the wiring. It's been a while since I've worked on one of these. 6 or 7 yrs. But the sensor was the next thing I was going to suggest. Also if the a/c works, when the selector is set to max the fan should run. "If you just ground it the car will run cooler" If you need to do that as a temporary fix that would be ok, but for the long term I would be concerned about fuel mileage issues and engine longevity. Brian

[UR50SLO]

It's been several years since I've seen one of these too But thankfully most GM cars use comon wire colors and I'm so usto doing Hybrids and conversions that I've memorized most of the wire colors and don't need to look much up.

I think that the A/C uses a seperate relay to opeate the fan as you described and it should operate when in MAX/Defrost/Norm. To cool the condensor.

Even if the fan runs at all times it might draw 20amps and shouldn't effect gas Mileage..? It'll only run as cool as the T-Stat allows. I've always run my cars cool... My nissan has 226,000mi... Fans run when it's runing..? I agree if a car is run cool and short distances that you'll need to change the oil alot more often than 3000mi.
What's the theory behind cool running engines and fans hurting gas mileage?
Just a question.. have not heard bad things about that.....?
Thanks, Scott~

[Bryan59EC]

My sister got by for a couple of years just making sure the AC or Def was on.
this was in a 86 Pont 6000.

My 88 Bonneville did the same thing, never did fix it, Just used the AC.
That car was used for 5 yrs like that--In Utah and Texas
That car is STILL running around San Antonio (sold 3 yrs ago)

Bryan

[brian0605]

Originally Posted by UR50SLO

It's been several years since I've seen one of these too But thankfully most GM cars use comon wire colors and I'm so usto doing Hybrids and conversions that I've memorized most of the wire colors and don't need to look much up.

I think that the A/C uses a seperate relay to opeate the fan as you described and it should operate when in MAX/Defrost/Norm. To cool the condensor.

Even if the fan runs at all times it might draw 20amps and shouldn't effect gas Mileage..? It'll only run as cool as the T-Stat allows. I've always run my cars cool... My nissan has 226,000mi... Fans run when it's runing..? I agree if a car is run cool and short distances that you'll need to change the oil alot more often than 3000mi.
What's the theory behind cool running engines and fans hurting gas mileage?
Just a question.. have not heard bad things about that.....?
Thanks, Scott~

Theory is if it does keep it cooler than normal the computer might not go into open loop and run on the base parameters of a cold engine.Using more fuel. It may not but I have seen it. It isn't the draw on the alt causing the fuel economy problem, that is minimal. And as you mentioned on the oil was exactly to what I was refering.

Originally Posted by Bryan59EC

My sister got by for a couple of years just making sure the AC or Def was on.
this was in a 86 Pont 6000.

My 88 Bonneville did the same thing, never did fix it, Just used the AC.
That car was used for 5 yrs like that--In Utah and Texas
That car is STILL running around San Antonio (sold 3 yrs ago)

That is fine for a temporary solution. But would you really want to recommend someone leave it that way? Please don't take offense, I am an ASE master certified tech and just can't recommend the statement above as a permanent solution. Brian

[Bryan59EC]

Originally Posted by brian0605

That is fine for a temporary solution. But would you really want to recommend someone leave it that way? Please don't take offense, I am an ASE master certified tech and just can't recommend the statement above as a permanent solution. Brian

Not if he is planning to keep the car for any length of time at all.
I personally did not have inclination to keep my Bonny running that long.
Ugly car--too many doors--had already been thru 2 girlfriends and 3 teen daughters. I was just waiting for it to drop dead .

Imagine my surprise when I saw it actually driving here in San Antonio, after I sold it for $200. 3 yrs ago. It had 250,000 miles on it, and I was just waiting for it to die.---Never did.

To this day I am not sure if my issue was computer related or switch related.
It quit working after an alternator spike killed the ignition, radio, every lamp in the car that was 'on' at the time. Many other gremlins popped up after that incident---just got tired of chasing them.

Bryan

[killerformula]

IMO if the car was mine...

Its 21 years old. Hardwire the fan on and leave it like that. Easy solution!

K

[UR50SLO]

Theory is if it does keep it cooler than normal the computer might not go into open loop and run on the base parameters of a cold engine.Using more fuel. It may not but I have seen it. It isn't the draw on the alt causing the fuel economy problem, that is minimal. And as you mentioned on the oil was exactly to what I was refering.

I think you ment "closed loop"

Open loop is before ecm get's told by the temperature sending unit (two wire connector (yellow/Black wires) that it is at XXX deg. and there is enough o2 cross counts to allow the ecm to go into "closed" loop where it runs off the O2 sensor and a few other sensors instead of as you had said "base parameteres".

If he leaves the factory rated T-stat in the car 195deg it will go into closed loop and will stay at that temp... no colder with fan running at all times. If he puts a 180 or 160deg t-stat in then yes.. the car will run that cool and might stay in open loop thus droping the gas milage....
Not being picky... I think you just ment to say Closed and put open
~Scott

[brian0605]

yeah I had editied it a few times changing the way I was tring to express what I was saying and missed it. Well hope he get it where he can drive it anyway!!

Originally Posted by Bryan59EC

Imagine my surprise when I saw it actually driving here in San Antonio, after I sold it for $200. 3 yrs ago. It had 250,000 miles on it, and I was just waiting for it to die.---Never did.

GM really made some strides in the mid 80's over the mid to late 70's and early 80's crap they produced. I had a 93 lumina 4dr sedan that I could burn the tire off from a dead stop at will. It had 190,000 when I traded it in. Brian