mY MANUAL SAYS A YELLOW WIRE RUNS FROM THE COMPUTER ON MY 84 tbi to the coolant fan switch located between the no. 6 and no. 8 cylinders. The switch is there and part of a yellow looking wire, but I cannot locate the yellow wire in a harness near the switch. Does anyone know which harness I should be looking in? Does the wire come from the frame, the firewall or across the valve cover?

 

It is time for a new book. There is no wire from the computer to anywhere near the fan circuit in an '84. Also, there should be no yellow wires associated with the fan. What are you trying to do? I'll bet a FSM would help.

RACE ON!!!

 

I'm tring to get the cooling fan to work the way GM intended it to. The fan was wired to be turned on manualy with a toggle switch when I bought the car. The black and red wire from the relay to the fan had been cut and the wire ran to a toggle switch. This bypasses the relay and overloads the wire from the battery to the toggle switch. The relay wiring seems correct except for the 12V constant hot wire going to a rust colored fuse link, it's dead. I will check the fuse link but I havent got to it yet. I tring to wire up the fan temp switch that is suppose to be located on the right side on the motor between cyls 6 and 8. There is no wire connected to this switch and I cannot find one to run to it.
I thought the temp switch wire should run to the fan relay. Then when it came up to 195 degrees it would pull in the relay turning on the fan but my manual does not show a wire running from the temp switch to the relay?
Im getting ready to just wire it up myself like I would any other hotrod but I pefer to keep it factory if I can. Thanks Wayne

 

I know the fan control on the 84's is different from the later models (CFI-EFI will advise ) but the wiring as is ,is done wrong.
When using manual switch it should switch the relay ; not the circut controlled by the relay which is how it is wired at present.

 

Very wrong! If I can get the fan working like factory, I am planning to wire up the toggle switch to pull in the relay just in case I ever need to manually run the fan.

 

The '84 is the only year with no computer interaction with the fan. Whatever book you are using, burn it or relegate to wheel chock, only duty, and get a FSM (Factory Service Manual). The relay powers the fan when the fan switch in the right side head senses the switching temp. The switch closes and completes the the circuit for the primary side of the relay by grounding it.
Repair the red/black wire from terminal "A" of the relay connector to the fan motor. Terminal "B" takes a dark green/white wire. That is the terminal and wire that eventually get grounded by the temp switch. Terminal "C" takes a dark blue wire that wends it's way to the "Fan" in the fuse block and is hot when the ignition switch is "On". Terminal "D" is the red, hot all the time, connection to the fusible link. Terminal "E" is not used.


The wire that connects to the fan switch is brown. The fan switch has a strange "mushroom head" connector like the knock sensor. You squeeze the wider part of the connector to release it from the switch.


The wire from the switch runs through a loom to a connector where it is joined by a tan wire from the A/C compressor in the same terminal. That connector goes through the fire wall and comes back out through another connector as the green/white wire to the fan relay. Are you starting to understand why I recommended the FSM? The fan won't come on at 195°. Your (stock) thermostat doesn't even open until 195°. Your FSM will advise you that the fan switch closes and starts the fan at 238°. I have my manual fan switch connected at terminal "B" of the fan relay. I also have a lower temp fan switch that turns the fan on at 206° and back off at 196°. Even so, my fan rarely runs.


There you go.

RACE ON!!!

 

For manual control ,all you need to do is to tap into the control wire from relay to head switch and run it to ground through a switch inside.
Check out
Fig. 12: 1984-85 Corvette Chassis Schematic

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

Grounding the DG/W wire closes the relay and turns fan on.

 

Great info. It should be a peice of cake now. My Manual just shows 85 and up C4s.
I looked up the manual in the link you posted and they stated that the wiring diagrams were not included so I guess I will keep looking for an assenbly manual somewhere with wiring. Thanks so much Wayne

 

From the '84 FSM:

 

Just a thought

Get one of those flex-o-lite switch kits. It gas a bulb that goes in the radiator and you can just wire it to the relay ground. I did this and can adjust where the fan(s) turn on from 170 and up.

Real simple to install and under 50 bucks

 

Or simply a lower temp fan switch for about $10.00.

RACE ON!!!

 

The OP said that he has wiring issues, this wouldn't address the issue though I do agree that this is a good solution if that was the only case. Finding different temp switches can be quite a task.

Mine is set but for everyone's benefit...where have you found lower temp switches and what are the part numbers?

 

The only one I have made note of is GM# 30531090, Blue Streak# TS136, which is fan on at 200° and fan off at 185°. I wish I had noted the number of the switch I am using. Of course, the fan switch only controls the auxiliary fan, except for the 1984. Specing a fan switch is pretty simple, really, with a sensor/switch catalog at hand. That is how I speced mine. He has to have wires to and from the fan relay to whatever switches the fan. To me, better a $10.00 switch than a $50.00 bulb/rheostat that will likely never be readjusted, once set.

RACE ON!!!

 

Good info...
You're right about the adjustment, I tweaked mine a couple of times so far but once I find the sweet spot I won't have to touch it.

 

I got the fan working. It comes on at 215F and off at 206F if I unplug the tan wire from the pressure switch mounted on the A/C compressor. Now I have to figure out the A/C wiring. The pressure switch could be stuck or faulty but I can't tell because the clutch does not pull in. I checked the clutch connector and there is no power to pull it in. I checked the fuse and it is good, but I cannot find the A/C relay to check the 12V supply. My Hayes manual is wrong about everything slse so i don't trust it anymore. Does it have an A/C relay? I also hotwired the clutch and it still does not pull in so I guess the next step is to replace the A/C clutch.