1987 cooling fan strange behavior?
Thread Starter
Heel & Toe
Joined: Dec 2012
Posts: 22
Likes: 0
From: Chambersburg Pennsylvania
1987 cooling fan strange behavior?
1987 Convertible had overheating Issues.
ThePrevious Owner Cut Out Both Relays For the Electric Fans. I Bought One Of The Relay Kits From ECklers And Replaced The main fan Relay.
Except Now The Fan Always runs. Plus the Relay Gets Hot. However the Entire Engine Bay Seems To Get Too Hot To Touch Is That Normal?
ThePrevious Owner Cut Out Both Relays For the Electric Fans. I Bought One Of The Relay Kits From ECklers And Replaced The main fan Relay.
Except Now The Fan Always runs. Plus the Relay Gets Hot. However the Entire Engine Bay Seems To Get Too Hot To Touch Is That Normal?
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
You don't state what the actual engine temp is or what the " overheating " problem was?
As it will if it is turned ON all the time ,
stock the fan only comes on at 228F and goes off when road speed is over 35MPH so the relay is never engaged full time
Thread Starter
Heel & Toe
Joined: Dec 2012
Posts: 22
Likes: 0
From: Chambersburg Pennsylvania
You don't state what the actual engine temp is or what the " overheating " problem was?
Engine Temps Usually RIse To 200 & Drop BackDown Until The Thermostat Closes Again With The NEw Fan.
I Guess My Problem Is That I Can't Get The Fans To Go Off AtThe Correct Time. They Run Immediately From key On And OnlyShut Off At Key off.
Relay Is Always EngageD Regardless Of Engine Temperature. A New Cooling Fan Motor Fixed The Overheating Issue. But I Had To Replace The CuT Relay Because The Po WIred A Manual Switch In.
Engine Temps Usually RIse To 200 & Drop BackDown Until The Thermostat Closes Again With The NEw Fan.
I Guess My Problem Is That I Can't Get The Fans To Go Off AtThe Correct Time. They Run Immediately From key On And OnlyShut Off At Key off.
Relay Is Always EngageD Regardless Of Engine Temperature. A New Cooling Fan Motor Fixed The Overheating Issue. But I Had To Replace The CuT Relay Because The Po WIred A Manual Switch In.
Team Owner
Joined: Jan 2003
Posts: 20,326
Likes: 252
From: Summerland B.C. Canada
Have you verified the correct relay wiring ?
ECM completes ground path for relay coil. If that wire is permanently grounded, the fan will always run. PO may have grounded it.
Use a meter and check if the green/white stripe wire at relay has continuity with ground. (key off)
Some info from my 86 service manual
http://members.shaw.ca/corvette86/Co...%20Control.pdf
ECM completes ground path for relay coil. If that wire is permanently grounded, the fan will always run. PO may have grounded it.
Use a meter and check if the green/white stripe wire at relay has continuity with ground. (key off)
Some info from my 86 service manual
http://members.shaw.ca/corvette86/Co...%20Control.pdf
Thread Starter
Heel & Toe
Joined: Dec 2012
Posts: 22
Likes: 0
From: Chambersburg Pennsylvania
[QUOTE=AGENT 86;1583970284]Have you verified the correct relay wiring ?
I Did continuity Checks Before I WIred It To Be Sure. One Red Wire Goes To battery The Other To ThE Fan. A Blue WIre To Ecm And A Green WIre To A Temperature Switch? IN the Drivers SideHead Which is Always Grounded.
ECM completes ground path for relay coil. If that wire is permanently grounded, the fan will always run. PO may have grounded it.
Use a meter and check if the green/white stripe wire at relay has continuity with ground. (key off)
Will Try that
I Did continuity Checks Before I WIred It To Be Sure. One Red Wire Goes To battery The Other To ThE Fan. A Blue WIre To Ecm And A Green WIre To A Temperature Switch? IN the Drivers SideHead Which is Always Grounded.
ECM completes ground path for relay coil. If that wire is permanently grounded, the fan will always run. PO may have grounded it.
Use a meter and check if the green/white stripe wire at relay has continuity with ground. (key off)
Will Try that
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Team Owner
Joined: Jan 2003
Posts: 20,326
Likes: 252
From: Summerland B.C. Canada
Which fan is currently stuck on ?
Thread Starter
Heel & Toe
Joined: Dec 2012
Posts: 22
Likes: 0
From: Chambersburg Pennsylvania
the primary fan is stuck on. from what I can see it seems like somehow i have the relays mixed up, but im not sure how because the red wire off the relay by the battery has continuity to the primary cooling fan. But it also has a green wire from a sensor in the driver side head. which would mean it should run the auxilary fan. The blue wire comes from the fuse box, that i can believe since there was no fuse in it and once i put one in the relay energized and the fan started running. So at this point I am completely lost.
Another thing, the sensor in the head completes the circuit regardless if its plugged in or not. im not sure if this is normal. before now the previous owner had a manual switch wired in where the relay was because the relay melted and it blew a fuse. Since the motor was going bad it drew more power and caused the blown fuse and relay. i replaced the motor and it runs 100x better than the old one.
Another thing, the sensor in the head completes the circuit regardless if its plugged in or not. im not sure if this is normal. before now the previous owner had a manual switch wired in where the relay was because the relay melted and it blew a fuse. Since the motor was going bad it drew more power and caused the blown fuse and relay. i replaced the motor and it runs 100x better than the old one.
Last edited by BBLACKHURST; May 23, 2013 at 05:41 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The sensor in the driver's side head turns on the auxiliary fan in front of the radiator, as shown in Agent 86's diagram. That's done by the "AUXILIARY COOLING FAN TEMPERATURE SWITCH" with the green wire. You can unplug the wire at the switch to find out how that affects your situation.
The fan behind the radiator is turned on by the ECM (Electronic Control Module). The ECM turns on the fan when the CTS (Coolant Temperature Sensor) in the front of the intake manifold tells the ECM that the coolant temperature is over 228°. If the connection from the ECM to the CTS is causing the fan to come on you can unplug the CTS, which will simulate very cold coolant, which should shut off the fan.
The ECM will also turn on the main fan if the A/C is running. You can remove that input as a cause by disconnecting the A/C pressure switch. It's located just above the frame on the passenger side. There are two switches there. The other switch controls the A/C compressor clutch. You can disconnect both of them for a test.
The fan behind the radiator is turned on by the ECM (Electronic Control Module). The ECM turns on the fan when the CTS (Coolant Temperature Sensor) in the front of the intake manifold tells the ECM that the coolant temperature is over 228°. If the connection from the ECM to the CTS is causing the fan to come on you can unplug the CTS, which will simulate very cold coolant, which should shut off the fan.
The ECM will also turn on the main fan if the A/C is running. You can remove that input as a cause by disconnecting the A/C pressure switch. It's located just above the frame on the passenger side. There are two switches there. The other switch controls the A/C compressor clutch. You can disconnect both of them for a test.