1986 Cooling fan won't work, Help!!!!!!!

[zamboni]

Help, my cooling fan won't work. I have replaced the cooling fan relay, but still luck! Where do I go from here?

Thanks for the help!!!!

 

[rrubel]

How hot is the engine coolant getting? The fan won't come on until 230 degrees with the stock ECU.

Things to check:

Try and get a voltmeter onto the harness leading to the fan motor and see if you're getting any current to it (with the engine at or above 230 degrees). Of course, be careful if the fan does decide to come on - they HURT.

With the engine off, see if you can freely spin the fan by hand and make sure it's not binding up.

You should be able to jump pins on the harness to the relay and see if the fan will come on manually - this may point to a bad coolant temp sensor, though I'd think you would see weird things on the dash as well.
[RICHR]

 

[vigman]

Depending on the Ilk.....

Either between cyl 6&8 Pass side or 1&3 Drivers side there is a sender......

It has a ROUND pin connection with a ( If memory serves ) a Green... or green & White wire. This line grounds when the engine is at 232 ( ish ) degrees.

Turn the key on.... get a test light


This wire ( Green/White) is the ground side of the relay. So with the wire pulled that line should show HOT IF the coil of the relay has power.

Remember it's the connector with the ROUND PIN not the spade lug... the spade lug is the temp gauge.

Ground the Green/ White wire

Does the relay go click?

Does the fan spin?

If the relay goes CLICK and the fan dosen't spin

Check the red wire going to the fan.. WITH the relay grounded!

Is the RED line HOT?

If the RED wire going to the FAN is hot but the fan dosent spin..... the fan is TOAST! OR the fan ground is bad ( typically the fan ground is OK)

If the red line ISNT hot...pull the relay and find the 2 BIG wires in the relay socket... Red & Orange..... see if the ORANGE is HOT... If not.. you have a burnt fusible link.... I will have to check the book for further info.


Hope this helps
( Did most from memory.. so it might be a tad inacurate ( Wire Colors)... but the base theory is correct)

Vig!

 

[zamboni]

OK, here's the rest of the details! The engine temp got to about 280 and started to boil out of the overflow tank. I needed a way to get the car home so a GM tech at a dealership in Souix Falls made a jumper for me that I put in the connector to the fan relay. (I was lucky that he would do that much since it was 530 PM when I pulled into the dealership.) This kept the fan working all the time... so when I parked for the night, I had to disconnect the jumper. This worked fine until I got it home to Council Bluffs (about 3 hours away.)

Now I am trying to zero in on what could be the fault. I had replaced the relay in Souix Falls, but didn't make any difference. I understand that there is a cooling fan sensor somewhere at the front of the engine. Is that the only sensor or switch that could cause the problem or are there other places to look?

BTW, does anyone have a picture of the engine/transmission that shows where all the sensors/relays/ switches are located?

Thanks!

 

[Tuck]

I recently had the same or at least similar problem-turned out to be a burned fusible link (like Vigman said earlier) but not sure if this is the same thing. I also replaced the fan relay but I could not get the fan to come on even when I jumped it. Doesn't sound the same since you have power to the relay.

A far as a picture of the sensors, I have a Chiltons manual (#28502) that does a pretty good job of showing the locations of all of the sensors, switches, valves etc. in Chapter 4. If I had a scanner I could send copies but I don't sorry. It is not perfect, some drawings are hard to decipher but so far it has been worth the money.

 

[Derek]

This happened to me also...it was the fuseable link that burned out.....its under the car below your feet.

 

[zamboni]

Thanks for the great replies!

Since I'm not sure what a "fuseable link" looks like, I'm having a hard time finding it. I have looked under the car, but the only wiring that is below your feet is some wiring into the engine and then it goes thru a hole in the firewall. I'm sure that is not what I am looking for. I have a lift, so it's no problem getting under the car, it's just that I don't know what I'm looking for!!

 

[Tuck]

Fusible link

Zamboni:
Fusible link is basically a specific type of wire that burns like a fuse when the load is too high. In my car and I am guessing yours since it is an 86 the fusible link is usually orange-and it will say right on it "fusible link" in white letters. You might want to check out my "ongoing saga" and discussion with Vigman under the topic "New version of Vette won't start". If you read through the post Vigman goes through fusible link 101 and actually details which link is the one for the fan (D I think).

Real quick (from my recent memory) there should be a short red wire (in addition to the main black one and maybe another red) coming out of the positive battery terminal. That wire should go to a black molded solid butt connector which is also a joint for another red wire which connects to a single wire GM connector (FYI this connector should go to another orange wire (also a fusible link) which heads back towards the firewall).

Coming out the other side (away from the battery) of the "black molded solid butt connector" should be a pair of fusible links-one of those should be for your fan. Both fusible links should go to a two-wire GM connector which goes to a orange and red wire which should diappear in your wiring harness down around the fender well.

If one of those fusible links is burned that would be your problem-if not I am not sure since you already replaced the relay and we know the fan works if you can jump it.


Hope this helps
Tuck

 

[zamboni]

Tuck,

Thanks for the "Fusible Link 101" discussion. After looking at the wiring diagram in the shop manual, I am wondering something. I am making an assumption that if I jump the fan relay harness (A-E), and the fan works, that it is not the fusible link. Is this a correct assumption?

I just had the coolant temp sensor replaced to fix a problem with the Overdrive, I don't think thast is the problem. Could I had a new (and bad) cooling fan relay?

This is fun, but I really need a scanner!!!!

 

[Tuck]

Yes you are correct-if you can jump A & E and the fan comes on than the fusible link can not be the problem since it must be good to provide power to E on the fan relay.

In looking back I mentioned that in my first reply. I did not think about that when you asked about the fusible links-sorry.

The cooling fan relay could be bad out of the box but I would try to check evreything else that you can before buying a new one.

Did you check the cooling fan fuse? There is a specific fuse in the panel for the fan. (I don't think you would be able to jump the relay if the fuse was blown-but I could be wrong)

Also did you check out the sender on the driverside of the block that Vigman replied to you about. If you pull it out and use a screw driver to ground it against the alternator the fan should come on-make sure the key is on.

 

[vigman]

A scanner wont help for this.

This is OLD fashioned wiring 101

And correct... IF you jump the relay your MAIN link in OK it's in the control circut ( Coil of the relay)... ground the line and see.

If they replaced the temp sender on the block for your overdrive problem... you got HOSED!

The overdrive temp sender is internal of the tranny!

WHOOPS!


Vig!

 

[vigman]

And IF you jump the ALDL connector

pins A&B your fan should come on from the ECM... which would point to the sender on the BLOCK.. and your relay is fine!



Vig!

 

[zamboni]

Boy, you guys must think I'm a real mechanic!!! I'll try to check the sender tomorrow.

As for your question --- I did check the fuse, it was fine.

BTW, the problem at the overdrive was that the temp sensor was reading low. It would only go to 99 degrees. Since it never got to the 140 degree area, the computer thought that the engine was still cold. Therefore the overdrive circuit wouldn't activate. Once my mechanic replaced the temp sensor, it has worked perfect ever since.

Vigman, Are you talking about jumping pins A and B from the electronic connector below the instrument panel inside the car or somewhere else?

I hope you don't think I'm a bumbling idiot. Trying to troubleshoot the electronic side of a car is something that I have never done very much of! Your help is greatly appreciated!

 

[zamboni]

Vigman,

The fan runs when I jump A&B on the ALDL. So it comes to the sender. I haven't found this sender described in the shopmanual, but I'll look on the car. Do you happen to know what the "official" name is? I'm sure that Chevy has some obscure name for it!!

Thanks again for the help.

 

[vigman]

Hmmmm

What about the post.... did you not understand?

Either between cyl 6&8 Pass side or 1&3 Drivers side there is a sender......

It has a ROUND pin connection with a ( If memory serves ) a Green... or green & White wire. This line grounds when the engine is at 232 ( ish ) degrees.

Turn the key on.... get a test light Etc Etc...

The sender is on the engine block

The plugs ( Driver side 1,3,5,7 / Passenger side 2,4,6,8)

The sender is on the head....

Let me know what clarification you need.


Vig!

 

[zamboni]

Vig,

I guess it didn't sink in until I started following the diagnostics in the shop manual. I have found the fan control switch attached to the high pressure line on the A/C on the right side of the engine between 6-8. I was looking for something on the block .... When I unplugged the switch and fired the car up, voila! the fan worked!!! The manual says to replace the fan control switch .. just like you said!!

Now, the question is - can I do this myself, or does this require the A/C to be purged of refrigerant? I noticed that some of the connections have schrader valves on them. If this is the case with the switch, then I think I can replace the switch myself otherwise I need to go to my A/C mechanic.

I really do appreciate your help!

 

[vigman]

Woah!

The line I ment... was ON the sensor ...ON the block.... not in the AC plumbing.... but that is a secondary line... when the AC shows ON the main fan kicks in... But this wasn't what I was refering to!


Well at least you found the cheesy bypass....

But the line you need to fix is NOT the one you found!


Vig!

 

[zamboni]

Vig,

I think I got you confused. My car does not have two fans on the radiator, only one. There is an option to put the secondary fan on the radiator. I noticed that in the shop manual it does show the secondary fan switches and relays.The switch for the secondary fan is on the block between 1-3.

Today I replaced the fan control switch that is in the AC line, and everything is back to normal!!!

Thanks for all your help. Your thoughts and ideas were invaluable!

 

[vigman]

1986 Main Fan 102 B

You have 3 senders

The one for the computer
(Foward on the intake manifold)
to tell the computer when 232 degrees was reached. The computer would OVERRIDE what ever was happening and engage the MAIN FAN.

The sender on the block was to DIRECTLY switch the relay on when the engine reached 230 Degrees... the sender closed and the circut completed (BYPASSING THE COMPUTER)

The 3 rd line was the AC request... when the ac engaged the MAIN fan ( with a delay on )
would be issued by the PRESSURE IN THE AC LINE... If it was cool outside and the car was in motion the main fan would not be needed.

BUT if the HIGH SIDE pressure exceeded a certian pressure... it WOULD kick the main fan ON to cool the A/C evaporator.

But as long as your happy!


Vig!