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C4 Electrical

Manual Override Switch (1/8)
 2/22/18 3:18pm
aldocar
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Joined: 12/3/2016
Posts: 74

I was thinking about installing a manual override switch is there an easy way to run the switch to the dash I can't find any access holes that lead through the fire wall, and by installing the override switch will the fans come on in the normal way when switch is off?  Thank you for your time, Al


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Re: Manual Override Switch (2/8)
 2/24/18 10:45am
Hot Rod Roy
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Mission Viejo, CA - USA

Vette(s):
Yellow '84 Coupe


Joined: 3/18/2015
Posts: 74

It's a bit of a mystery, but I consulted with my very smart psychic wife, and she opined that you probably have an '88 Corvette.  Wink

And she thought that you're probably asking about activating your radiator fan with a switch.   Your question doesn't give us much of a clue, but since she's usually correct, I go with that.   Wink

She suggested that you fill in your personal information, so I wouldn't have to bug her so often!   Wink

I'm not sure when they converted to the computer controlled fan, but If the '88 is like my '84, here's my technique:  
The wiring from the Coolant Temp Switch (CTS) in the head goes to the fan relay, which is located on the LH inner fender panel, below the brake master cylinder.   On your '88, I'm not sure whether the CTS is in the LH or the RH head.   In my '84, it's in the RH head, between cyl 6 & 8.   I think yours might be between 1 & 3.
The wiring goes thru the firewall connector as a loop between the engine harness and the body harness, so the wiring is already thru the firewall!   This connector is to the left of where the steering column goes thru the firewall.   A switch between that loop and ground will activate the relay!   An even more useful feature is an LED on that wire to indicate when the fan is activated!   


(large image modified to link-aapple)



|UPDATED|2/24/2018 7:45:27 AM (AZT)|/UPDATED|


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Re: Manual Override Switch (3/8)
 2/22/18 8:51pm
aldocar
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Joined: 12/3/2016
Posts: 74

Your wife is right on that is what I was referring to. Thank you for the information. With the  switch off will the fans come on in the normal way? The primary comes on at 217 to 221 deg. and the auxiliary at 230 deg. I will up date my profile. 

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CTS for Radiator Fan (4/8)
 3/4/18 3:00am
Hot Rod Roy
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Mission Viejo, CA - USA

Vette(s):
Yellow '84 Coupe


Joined: 3/18/2015
Posts: 74

Thank you for the PM with more details on your question.   There is a hazard for installing a CTS with the 195/170 turn on/turn off rating.   If your thermostat isn't open all the way when your fan turns on, the thermostat and the CTS will be working against each other.   The CTS will be operating the fan to reduce the coolant temperature, which will cause the thermostat to reduce the coolant flow, in an attempt to increase the engine temperature!   The result will be that the fan will run all the time, since the engine temperature will never go down to the 170 turn off temperature.

The CTS can be changed without draining the coolant.   Be sure the thread size of your CTS is correct (there are differences).  Apply a thread sealing compound, but don't use teflon tape.  The housing of the sensor must be a good ground.   Engine cold (of course).  Open the rad cap to relieve any residual pressure.  Replace the cap.  Work quickly to replace the CTS.

It sounds to me like your engine temperatures are just fine without changing anything.

Cool

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Re: Manual Override Switch (5/8)
 3/4/18 11:03am
aldocar
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Joined: 12/3/2016
Posts: 74

I was thinking the same on the fans running all the time. The car has survived 30 years running with the stock set up, you are right I will leave it stock and thank you for your information. 

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Re: Manual Override Switch (6/8)
 3/9/18 1:57am
garyjackso
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Perkinston, MS - USA

Vette(s):
1993 40th Anniversary Coupe


Joined: 3/8/2018
Posts: 4

Hello to All:
 
I am puzzling over this same problem.........I think.  My 1993 ran fine at 194 degrees until a couple of weeks ago when the temp started spiking to 230, then dropping back to the 200-205 range.  It cycles. Both fans are working.  I replaced my temp sensor in the front center of the block about a month ago with a generic, and used Teflon tape.   Suggestions ??


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Re: Manual Override Switch (7/8)
 3/11/18 5:27pm
Hot Rod Roy
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Mission Viejo, CA - USA

Vette(s):
Yellow '84 Coupe


Joined: 3/18/2015
Posts: 74

garyjackso said: Hello to All:
 
I am puzzling over this same problem.........I think.  My 1993 ran fine at 194 degrees until a couple of weeks ago when the temp started spiking to 230, then dropping back to the 200-205 range.  It cycles. Both fans are working.  I replaced my temp sensor in the front center of the block about a month ago with a generic, and used Teflon tape.   Suggestions ??


Welcome to the Forum, Gary.  Your question is entirely different than the OP's question.   This "thread" (series of responses) should be related to the heading "Manual Override Switch".  When somebody throws in an unrelated question, we call it a "hijack", but I'll respond anyway.

I doubt your sudden change of temperature is related to your sensor change.   Why did you change the sensor?   As you probably know, that sensor provides info for the ECM to control your fuel injectors, pollution control, and your engine fans.   The sensor housing provides a ground path, and as such, needs a good electrical connection to ground.   Teflon tape on a sensor isn't a good idea.   Use a good gasket sealant or thread compound rather than teflon tape.

My first suggestion on sudden change of engine temp:  be sure you haven't collected some junk in your radiator air path!  Flush the fins, and check for crud between the a/c condenser and your radiator.

Second suggestion: you may need a new thermostat.   I'm presuming your engine coolant is changed regularly.

Cool


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Re: Manual Override Switch (8/8)
 3/21/18 11:07pm
garyjackso
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Perkinston, MS - USA

Vette(s):
1993 40th Anniversary Coupe


Joined: 3/8/2018
Posts: 4

MANY THANKS  !!   I followed your recipe, and the running temp is back down in the 194-200 range.   Sorry about the "HighJack".....it was unintentional.

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