Sid.123

I have an 86 c4...There is a lot of talk on here about fans and cooling, main fan, aux fan, on/off tempreture settings etc...
Mine at some point has had a new aluminium rad fitted and it has only one fan. On the side nearest the engine and this is run via the aux fan relay on the drivers side wheel arch.
Am I right in thinking there should be two fans? One on each side of the radiator?
There must be a temp sensor issue as the fan is controlled by a switch in the car that earths out the primary windings in the relay, Switching the fan on.
There is no single wire sensor on either head that I believe would control this. There is a single wire sensor on the radiator itself but its plastic with a central electrode that goes into the coolant. Being plastic it cant ground itself and so can only be a sensor, not a switch.


This is not a problem in itself and I'm only realy putting this on here for imformation.
I will Look at some point to see if I have wiring for another fan on the front side of the radiator as the main fan relay is still there on the passenger side firewall.
A lot has been chopped n mucked about with in its 30 year life span.but bit by bit we will sort it.

JackDidley

2nd fan was part of an option package. Z51, I think. There is a temp sensor at the front of the intake that tells the ecm the temp. The ecm turns the fan on and off.

WVZR-1

If your SPID label is still on the car post a snapshot of it so it can be determined just how yours "should be/would be" if original. SPID for an '86 I believe for most is on the console lid but early cars it's in a rear storage compartment (driver side I believe). In '86 I believe only cars with RPO B4P had the AUX FAN but there were other options that generally appeared also with it but not actually required.

There's an '86 SPID in this thread post #1

https://www.corvetteforum.com/forums...code-help.html

Churchkey

May have an after market fan installed a pic would help to get the issue sorted.

If after market fan an automatic fan control with adjustable turn on temp is available.

Link: https://www.summitracing.com/parts/flx-31147

Sid.123

Here's a pic of what I have if you can see...

Sid.123

Here is a pic of my vehicle details

WVZR-1

This is location of COOLING FAN RELAY (NOT AUX) for your car. User "Cliff Harris" posted this and there's no reason to doubt this. So it's safe to assume that in some fashion your switch (to earth) inside of car is a modification of sorts to maybe the original circuit.



Your SPID indicates there was NOT an AUX FAN on your car in it's "as built" original configuration.

You might post a snapshot of this "thought to be" fan relay - it is NOT.

Your car "as built" would have only one sender/sensor in the cylinder head and that would be for the cluster temp gauge. Left head between 1 & 3 below alternator. If another in the RH cylinder head it's maybe added by someone. It's use? Undetermined.

The single wire plastic device in the RH radiator tank is a low coolant level sensor/switch.

Do you have the FSM for your car?

Ray Quayle

Dave, I'm pretty sure that on the '86, there was no early/late difference on the gauge sender and it is located in the right head between 6 an 8.

Sid.123

its very confusing as to what years have what sensors.
I thought I'd just run the car up to temperature and see what happens and would you believe it it works ok without using the switch at all turning itself on n off as it should. Why was the switch fitted? Don't know can only guess they wanted extra cooling.
Will still check out the other relay on the passenger side to see where that goes.

WVZR-1

Hello Ray,

I checked the FSM for an '86 again and it's quite specific as to the location of the IC TEMP SENDER, left side engine below alternator 8A-82-4

FSM in error? It certainly wouldn't be the first error.

I've never owned an '86 and don't recall a friend with one so I'm relying on what I read. I went back to my '86 FSM and there's things I'm NOT accustomed to seeing. The wiring circuit index mentions 35 for IC TEMP (as we all expect) and mentions DK GREEN like we all expect but the cluster diagram isn't consistent from the IC to the sender. Here's the '86 IC diagram 8A-82-1(note 35 TEMP SENDER)





Here's the "location" mentioned 8A-82-4



This is from 6D5-3





Maybe the OP will mention his and maybe Cliff will stop by and mention what he's found and stumbled upon through the years.

Ray Quayle

Yea, the FSM! Can't live with it, can't live without it. Much of the '86 FSM was a carryover from the '85. Some was corrected in the Supplement, but not all. For the '86 MY, exactly when is open to debate, the IP coolant sender was moved from the left head, where it had been in '85, to the right head. If fitted the Aux Fan sender, the Aux Fan sender was installed in the left. Both of the senders fitted as they were in '87 which has a correct FSM for these circuits. I'm the original owner of my '86 Pace Car and have worked on many '86s in the last 30 years and I've not seen any configured as the FSM states. But I've not worked on any very early examples, although some were early enough to have iron heads and passenger side mounted scissor hood prop. The OP has no Aux Fan, so if I'm right, he'll have no sender in the left head between 1 and 3, assuming the switch he mentions is the only alteration from factory, he'll have a single spade connector sender in the right head between 6 and 8.

Sid.123

Ray...Your right what you say...I haven't got an sensors on the left head...There is a single terminal sensor on the right head between 6 n 8 and a sensor by the top hose elbow on the front of the intake manifold

Ray Quayle

As it should be. Thanks for the confirmation.

Sid.123

now we have established that my car only has one fan there is still the question about the relay on the other side, a pic is included to help

Ray Quayle

Sid, That is the relay for the HVAC fan, not an engine cooling fan.

Sid.123

duh... Ok.. Didn't even give that a thought..was so wrapped up in my cooling fan issues. Thanks