Important! Cooling fan issue HELP !

[VIN_#_00521__Z-51_C4]

Need help with this......................

My '84 ( when i bought it, Never had a properlly functioning fan switch.... I knew it had the problem, and added a switch to turn it on at a certain temp, I have replaced it and it still will not turn on at temp ( What is the turn-on temp for theses vettes, i heard 240 and it definately did not turn on at 240 even 260 when the coolant was starting to Boil over in the bottle.........Heres another thing the wierd behavior i have noticed with the fan switch.........i was driving home and did not turn on the switch as i was on the Highway Did not notice a change in temp it hovered @ 207 all the way

I pull in to the Oreillys to buy fuses and when i shut the car off..... The fan is running on its own( it switched on while driving ) Heres the Kicker! I never turned on the switch( that will turn it on manually ) it was running but at a slower speed, I flipped the switch and it picked up speed, turned the switch off and it was still running after a while it shut down on its own................I did put in a new battery recently and had the cables unhooked for awhile while i installed the battery is it the fan itself or maybe a Relay to the fan because i just changed it Does that relay help it turn on at the right temp or allow it to function period

Any suggestions i need them fast


What would make it kick on and stay running then shut off long after the car was shut off now I have a new fan switch in and it will not switch on by itself is the Temp switch bad, should i change out the stat

Any Help with this would be appreciated

 

[vetteoz]

I'm confused.
What is your current setup? A temp switch and manual over ride switch in parallel or just the manual switch?

 

[vetteboy86]

That is a sweet ride:cool

The relay only controls the function of the fan. The fans in these C4's as has been discussed comes on at a very high temperature. That is how they were designed for things including emissions.

I'm wondering if you have an intermittent ground issue? Does the fan come on every time you manually turn it on? How do you have that wired? Using existing circuitry or by other means?

 

[Hib Halverson]

The fan relay does not control the fan on temperature.

All the relay does is allow the small current of the cooling fan temperature switch control the the larger current required by the cooling fans. It's difficult to accurately diagnose this problem without seeing how the additional, manual switch was installed, but I'm going to guess that, as "vetteoz" suggests above, that your manual switch is not wired properly. Also there could be or a problem with a ground or the fan relay has a problem.

Lastly, a better way to control fan on temp with that car is to install a lower temperature cooling fan temperature switch--the switch (which looks like a sensor) that is screwed into the left head between the #1 and #3 exhaust ports.

I should add that after I posted the first part of this, I went upstairs where I keep all my service manuals and was reading the 84 book. Interestingly, there's little information in the book on the cooling fan system...not even a wiring diagram but there was some component locator drawings.

My guess is the current flows from the key switch "run" position to fan relay control circuit and then to the switch and, when the ECT reaches the switches "on" value, the switch grounds and and current flows through the relay.

The battery connects to the fan relay load side then to the fan motor and then to ground.

Current flow through the relay control circuit that energizes the relay which closes the circuit running from the battery to the fan and the fan kicks on.

 

[Schrade]

Wiring in switches and by-passes is really not the way to repair or maintain a car, IMO, especially a vette.

If you DO do something like this, you need to draw a schematic for what you've done, because no one else will be able to help answer a DIFFERENT problem. Plus, it would be best to know what's wrong with the ORIGINAL circuit, which you'd have to diagnose to know.

This is why the other poster asked if you put the new switch in series, with the same ground, or in parallel with a dedicated ground.

Do you have a multimeter? FSM?

 

[geekinavette]

As Hib said....without knowing how this "extra" switch is wired up it is difficult to diagnose. With that said...

By referring to the cooling fan wiring diagram:

The way the cooling fan operation works: The relay has 4 contacts, two for the normally open switch, two for the magnetic coil. Battery voltage is applied to one side of the switch and one side of the coil. When the other side of the coil is connected to ground, either by the temperature switch or the AC pressure switch, current flows through the coil creating a magnetic field within the relay, that magnetic field "pulls" the switch contacts closed (somewhat backwards from the way they have it drawn...but that's what it does), which provides voltage to the other side of the switch turning on the cooling fan.

The assumption here is that your "extra" switch is simply wired in parallel with the two existing switches, allowing you to manually pull the negative side of the relay coil to ground. If it is not connected like that....then it was done wrong.

So...if you're good enough with using a voltmeter and wiring diagrams to check connections....then with that diagram you should be able to figure it out. If not, then you should recruit the assistance of someone that is.

Now these relay switches are indeed known to "stick" in the closed position...had one that did that myself. It IS a mechanical device...and mechanical devices wear out! They are not expensive...there's no harm in simply replacing it (I would for no more than they cost). This however is only going to address the "stuck on" condition...and only potentially.

Good luck!

Bill

 

[VIN_#_00521__Z-51_C4]

one wire to the battery terminal and one tapped into the power wire of the fan that is run to a 2 terminal switch do you think the Relay is toast if the fan doesn't come on? Once the fan switch was installed I un-hooked the manual switch from the power wire of the fan and it wont kick on at temp ( especially when sitting at a traffic light, it will creep up past 220* if i am moving and on the Hwy it will probably stay around 209 w/o the fan what is it that i have hooked up wrong

 

[gmjunkie]

Wiring in switches and by-passes is really not the way to repair or maintain a car, IMO, especially a vette.

If you DO do something like this, you need to draw a schematic for what you've done, because no one else will be able to help answer a DIFFERENT problem. Plus, it would be best to know what's wrong with the ORIGINAL circuit, which you'd have to diagnose to know.

This is why the other poster asked if you put the new switch in series, with the same ground, or in parallel with a dedicated ground.

Do you have a multimeter? FSM?

Way more times than NOT,I repair SEVERE electrical problems on these cars with nothing more than a VOM,Contact Cleaner,Wire Brush,Sand Paper and Boeshield T-9!!
High Resistance and Bad GROUNDS make Electrical Systems do ALL sorts of Weird Things!!

 

[VIN_#_00521__Z-51_C4]

Thanks for the nice compliments( I really love this car )

 

[G Winter]

one wire to the battery terminal and one tapped into the power wire of the fan that is run to a 2 terminal switch do you think the Relay is toast if the fan doesn't come on? Once the fan switch was installed I un-hooked the manual switch from the power wire of the fan and it wont kick on at temp ( especially when sitting at a traffic light, it will creep up past 220* if i am moving and on the Hwy it will probably stay around 209 w/o the fan what is it that i have hooked up wrong

This is not a good way to wire a switch in. You are putting the full load of the fan through your switch. I think you stand a good chance of burning up your car with it wired this way.

I have a switch wired to my 90 for supplement to get a head start in hot weather in slow traffic. I wired to the ground of each relay to a double pole single throw switch wired to ground. The 90 has two fans, two relays. Single fan single relay a single pole switch is fine. On the double fan the relays need to be isolated to keep the rest of the system working like it should.

You could have a bad relay. If contacts are burnt it would be the same as a bad ground. Can cause intermittent problems. With switch on jumper the ground wire on the relay coil to a good ground point and see if relay actuates and fan runs. If fan does not run or runs slow , replace the relay.

Glenn

 

[geekinavette]

This is not a good way to wire a switch in.

Not only "not good"...but downright dangerous!

Get rid of that switch and its associated bubba wiring, period. Get it working like it was designed to work.

 

[Schrade]

one wire to the battery terminal and one tapped into the power wire of the fan that is run to a 2 terminal switch do you think the Relay is toast if the fan doesn't come on?

By the bypass you describe, the relay is out of the circuit.

You need to take pictures of the by-pass as you have it, OR, save geek's schematic into your pc, and edit it with a photo-editing app, and as simply as you can, describe what you've got.

If you do one or the other as described COMPLETELY, many people here will be able right away to say what's wrong. In fact, you might even figure it out yourself as you do it.

Electric flow is just like water in a hose. A valve (switch) can stop flow to the nozzle, as can a cut hose (short circuit)...

 

[Hib Halverson]

Again, a manual switch is not a very good way to control the fans. A much better way is a 180 or 190 deg. coolant switch.

That said, if one IS going to use a manual switch, wiring it to directly control the fans is an undesireable way to do the job unless the switch's current capacity is higher than the current draw of the fan which is probably 20 amps and the wire used is a low enough gauge to safely handle that current.

I think, the best way to install a manual bypass switch on an engine that uses a simple coolant temp. switch to control the fan is to connect the switch in parallel with the coolant temperature switch. Splice into the wire between the fan relay and the coolant switch. Run a wire from there to your switch inside the car. Then run a second wire from the other pole of that switch to ground.

 

[VIN_#_00521__Z-51_C4]

Thanks for the advice all the tips given will help I am probably going to take the switch off I'll go with what Hib said I found that the FUSEABLE Link from the Battery to the Fan power wire was all burned up and the connecter was melted I have changed it now and i have to see if the fans will kick on other than that i did talk with a seasoned mechanic and he said that switch I have( rated @ 30 amps with an in-line fuse of 30 amps ) would be ok and he did not see anything wrong with it ( i may go to his shop monday and check everything with a voltage meter to make sure the systen and the relays are working

 

[Hib Halverson]

GM used to sell a "lower temperature" coolant temperature switch but I'll be darned if I can find the part number for it. I'll bet some of the aftermarket electric fan vendors, such as SPAL sell such a thing.

 

[VIN_#_00521__Z-51_C4]

GM used to sell a "lower temperature" coolant temperature switch but I'll be darned if I can find the part number for it. I'll bet some of the aftermarket electric fan vendors, such as SPAL sell such a thing.

Well I probably won't change out the fan switch anytime soon, I just got it installed thinking that the fan would kick on once i had replaced it and it didn't do anything for it

I found a BUTTT connecter that was on the fuse-able link(all melted and charred ) i fixed that and nothing happened It maybe the Fan Relay( can you tell me where the fan relay is located there is a relay on the Drivers side of the car, on the engine-side of the wheel well NEAR the Battery positive terminal ___ It that where the relay is located


Still looking for solutions here It's not complete fixed and im not out of the woods yet

 

[vetteboy86]

I'm not entirely sure if that is the relay or not, but you should be able to follow hot side of the cooling fan. The ground side is probably grounded near the fan. Tracking one wire might be a possible solution to finding the relay.

 

[Schrade]

Thanks for the advice all the tips given will help I am probably going to take the switch off I'll go with what Hib said I found that the FUSEABLE Link from the Battery to the Fan power wire was all burned up and the connecter was melted I have changed it now and i have to see if the fans will kick on...

"...IF the fans kick on"???

The fusible link bailed cause something was wrong. I think you should NOT have replaced it until you found the problem. If someone did some work, and didn't properly secure a harness that's now chafing somewhere, it's gonna' go belly up again. I think you need to follow the circuit FIRST to its ground, to see if the problem is in THAT circuit alone.

If not, you'll have to follow the circuit to the 12V SOURCE, to see if there's a problem in the supply harness, which could affect other circuits in the same harness.

Not fun, but but more fun than putting butter on your whole car if it turns into a giant piece of

 

[CorvetteArchives]

Relay location? It IS on the driver's side wheelwell. The stock 84 connector looks like the one in the FIRST picture. If your connector looks like the SECOND picture it is possible someone tried to upgrade the relay and screwed up the wiring.
In any case I'd personally ditch the auxilary fan switch, as you were leaning toward, and go with a stock setup. Temp is easily controlled with a new lower temp fan switch as Hib mentioned.