dragonmas

1987 Camaro z28 Vert. 305 TPI changed to Carb.Coolant fan stopped working. Fuse good, have 12volts at fan connector with switch on. Relay seems to be working. Is this fan always on with switch in run or is it also controlled by a coolant fan switch? Also if fan is bad is there a new/retro fan that will work?
Thanks

sofakingdom

iTrader: (1)

No, absolutely not.

Yes there is a switch: pass side head, between #6 & #8 spark plugs. Should turn the fan on when the coolant temp reaches about 235°F.

Coolant fan logic:

A/C on = fan on
Temp above 235°ish = fan on
All other conditions = fan off

AFAIK you can still buy a new replacement fan motor from any number of sources; rockauto.com would be a great place to start. They're surprisingly few $$$.

John in RI

iTrader: (167)

A TPI would only have a coolant sensor in the pass side head if the car had duel fans. On single fan TPIs the ECM was responsible for turning on the coolant fan. Since the car is no longer a TPI,.... the ECM will no longer be able to provide the "fan on" signal.

Most factory carb Thirdgens didn't get an electric fan, but those that did had the coolant fan switch in the pass side head. If you expect to use an electric fan rather than a clutch fan remember that a relay should be used to supply a coolant fan with power due to the amount of power needed to run it. Most relays need full time (HOT) power, full time Ground, switched power ( Ignition), and switched ground (signal) to turn the accessory (fan in this case ) ON/OFF. Here is the schematic for the electric cooling fan from an 85 Carb V8,... you can use it to build your own system using factory parts.

dragonmas

I replaced the fan motor and all is well. There is no coolant fan switch. The motor is just tied in with the coolant fan relay to run when the switch is in run.

Mymynd

I have a related question, this has been puzzling me forever. Ok so the fan works normally, however sometimes it doesn't turn on (I can activate it with the AC so I know that the relay is good). Even more puzzling, if I quickly restart the car and the temp is above that needed to activate the switch, the fan comes on. So I know the switch works, I assume the problem (based on your above schematic is in the junction between the switch and AC. Can you possibly provide a solution? Should I use contact cleaner on the junction once I find it, or possibly replace it? Or could this be a different problem?

henryd3

iTrader: (128)

It sounds like it's working just fine. When or where is there a problem here?
In what situation is it not operating as it should?

Mymynd

It intermittently will just not turn on. Sometimes it cycles a few times then won't come on again or sometimes it comes on late or not at all....unless I use the AC to turn it on, or restart the car

John in RI

iTrader: (167)

Mymynd:

Sounds like a relay problem to me........ could also be a failing temp switch in the head. Your 84 Z28 should have a factory electric fan that is the same as the diagram I posted earlier in this thread. None of the info I'm about to write means ANYTHING if your electric fan is not a stick fan !

You reported that the AC setting on the heater/AC controller will always kick the fan on when moved to an AC setting. That seems to indicate that the fusible link is OK, the Grounds ( Fan and AC controller ) are OK and the throttle kicker is OK. The issue seems to be only when the switch should be sending a ground signal to the relay.

I'd suggest removing the plug from the coolant switch for inspection. You might simply have a bad wire / plug (VERY Common). Then; turn the key to RUN and apply a ground wire to the coolant switch to see if the fans turn on as they should - repeatedly. If there is no problem at the switch's' plug,...... I'd throw some $$ at a new relay.

That's where I would start.......

Mymynd

Already replaced relay and gone through 3 fan switches. I also replaced as much of the wire to the switch as I could see and the connector. Plus, if that were the case, restarting the car shouldn't cause the switch to activate the fan. I'm going to try contact cleaner and replacing the fan switch wire to the AC junction completely

henryd3

iTrader: (128)

That kind of intermittent failure practically screams out faulty wiring or weak connections. Check for good clean ground on the fan as well

John in RI

iTrader: (167)

Sure seems like a problem on the green wire to the switch, the plug, or the switch itself to me. The AC controller is on the same exact circuit as the switch, so if 1 of them works and the other one doesn't,.........

Check power from the throttle kicker relay when the fan fails to come on @ 238 degrees as it should. That relay gets power only when in RUN so MAYBE it works when first activated (re-start),..... then fails while in use. (I'm just guessing now ! )

Mymynd

John that would make sense if the AC didn't make the fan come on because (according to diagram) all the AC does is ground the same wire going into the relay. Also it cycles normally at times. I am 98% sure I have a wiring issue, can somebody tell me where that splice (s163) and what connector that is (c109). I plan to replace the wire to that splice point, upgrade the splice and then replace the connector once I have a part number. My service manual must be from early 84 and does not have that cooling fan circuit. The other possibility (imho) is that the engine could have a ground issue that for some reason restarting the car fixes

BTW seriously thank all of you for all your help this problem has been driving me nuts.
Btw I have a jet fan switch mine pops on at 165

Mymynd

I will try to trace the fan ground down. Also thinking of replacing fan motor for ***** and giggles

John in RI

iTrader: (167)

Pretty sure C109 is the Heater/ AC wiring harness connector - usually screwed to the firewall in the engine bay near the heater core lines. The factory Splice is somewhere inside the Engine harness itself.

Make sure that the gauge reading is accurate,..... It's VERY important when dealing with "however sometimes it doesn't turn on" problems. & Good luck !