86, Excellent info! clear n to the point.
thanks
Dave

 

Yes, great info, but with one inaccuracy. THE fan on an '84, (there was no auxiliary fan available in 1984), comes on at 238°. That is a higher temp than any other year. Therefore, are you sure the fan isn't working? To test the fan operation, motor, relay, and wiring, remove the wire from the fan switch on the right side of the engine, located in the head between the #6 and #8 spark plugs. Regardless of engine temp, with the ignition switch in the "On" position, ground the wire. When the wire is grounded, the fan should run. If not, you can methodically check for (troubleshoot) the cause of the fan not running. If the fan does run with the brown wire (ckt 335) grounded, about the only possibility of an inoperable fan, if indeed it is, is a bad fan switch. Unfortunately, the only way to test the switch is to heat it to the activation temp.

The same ckt 335 connects to a switch on the A/C compressor (with a single tan wire) and grounds with the A/C on. The 1984 has several idiosyncrasies that didn't survive beyond the 1984 model year.

RACE ON!!!

 

I believe the sensor on the pass head (84-87) is for temp gauge operation only. The switch didnt come into play till late 87, I thought. I could be wrong, let me know

 

CFI thanks!! If I understand this correctly, as long as 335 sees a ground the fan will run. I know the fan runs because if I shut the car off the turn the ign to run the fan will come on. I did not realize that the "fan on" set point was so hot. looks like GM used a idiot light switch to run the fan. I gotta figure out something that will work better.

I am thinking about cutting a fill cap and burp hose to a reservoir into the upper rad hose to simplify coolant fill.


again Thanks
Dave

 

No need. You can simplify coolant fill by drilling one very small hole into the thermostat which helps with burping trapped air, yet won't delay warm up time.

Yes, he's right. The factory fan's kick on temp is that high. I don't like my temps that high so I kick my fan on sooner with an aftermarket switch.

Consider installing a low temp fan switch. A lot easier than reprograming your chip. Very quick, easy, and inexpensive. It kicks on your fan at 200 degrees instead, and back off 185. Also a lower temp thermostat like a 160 will allow the coolant to circulate sooner than the factory one does.

I use this one:
http://www.mamotorworks.com/corvette?frame=3.944

With this fan switch an a 170 degree stat, my car never goes above 205 degrees even in the hottest of days in traffic, or when I used to use my car for local parades. With the lower stat, the fan isn't constantly running either since the coolant is allowed to circulate sooner than factory. If you use a high temp stat like a 195 or something like that, the fan and stat will tend to fight each other cause they are too close together.

 

prefect! got one coming good time to do the tstat too.

 

Just the opposite.The Left side is for the gauge. Right side is the Fan switch of which you can buy one that will make the fan (only one) come on at a lower temperture like 170 to 180F.A 160 TS is required though.

 

You can't compare your '95 and '96 to the early cars, different setup. Compared to yours he's wrong, compared to mine, he's right.

There is always confusion whenever this topic is brought up. I will clarify '84-89' below.

All '84's came with a single fan setup as CFI stated. Fan switch is on passenger side head, between plugs #6 and #8. No dual fan option for '84. Only year where a single fan car has a fan switch threaded into the head.

Dual fans became an option beginning in '85.

Only dual fan cars have a fan switch on one of the heads. This fan switch activates the "auxiliary" or "secondary" fan. It can also be referred as the "auxiliary fan switch".

Single fan cars have no fan switch. There is a pipe plug with a squared hole there instead.

Primary fan is always controlled by the ECM and not the switch in either setup, except '84.

Here's the pipe plug I removed out of my single fan car to install this low temp switch on driver's side head:



I had to custom grind a slighly larger pipe plug socket to fit the odd sized hole because I couldn't find the right size anywhere. Every size either too big, or fit too loose. Took a 3 foot breaker bar to remove it. That bastard was on there tight. If you have dual fans, you'll simply swap out your stock switch.

85
On 85's with dual fans, the fan switch is sometimes on the driver's side between #1 and #3, and sometimes on the passenger side between #6 and #8.

86-89
On '86-'89 the fan switch is on the driver's side head between plugs #1 and #3.

The fan switch is identified by a round plastic push in connection. Just like the knock sensor.


The dash Gage temp sender has a single square shape spade terminal, located opposite of the switch.