Coolant Temp Problems
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 25
Likes: 2
Coolant Temp Problems
Kinda a long story but i have a 1985 corvette and i was having problems with my rad fan not wanting to turn on i assumed the relay was probably bad and ordered a new one and though while i was at it i might as well change the fan temp switch out for a 190° on instead of stock 215° or whatever stock is. There were no instructions for how to wire the new temp switch and i tried wiring it to a different relay but with no wire diagram on how to do it it failed. So i attached the factory blue cable to it because at worse im back to where i started with having no fan running. When running the interior temp guage will say the car is either at 300 or low with no inbetween. Does anyone have a suggetion on what i should do. Should i just go back to factory everything, or does anyone have a good wire diagram or photos of how they wired it up. Or should it just work with the factory wire and there is something else wrong
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 25
Likes: 2
To make a little more sense, currently my rad fan didnt work and idk y i put a new relay on in case that was the problem but have no way of knowing until it reaches temp. I would like to lower the fan turn on temp to 190° on instead of the factory temp which is why i got a new cooling fan temp switch which could also be the problem but idk how to wire it correctly. And with the new temp switch on i no longer have an accurate temp guage.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
The fan is controlled by the ECM. It sounds like you swapped the coolant temp sensor in the cylinder head that sends signal to the temp gauge in your dash, for a temp switch....thinking that would change your fan temps?
I believe that the two ways to get your fan to come on at a lower temp are:
1. reprogram that parameter in the ECM
2. Wire up your own temp switches, relay(s) and run the fan that way.
I believe that the two ways to get your fan to come on at a lower temp are:
1. reprogram that parameter in the ECM
2. Wire up your own temp switches, relay(s) and run the fan that way.
Le Mans Master
Joined: Jul 2004
Posts: 6,228
Likes: 698
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Kinda a long story but i have a 1985 corvette and i was having problems with my rad fan not wanting to turn on i assumed the relay was probably bad and ordered a new one and though while i was at it i might as well change the fan temp switch out for a 190° on instead of stock 215° or whatever stock is. There were no instructions for how to wire the new temp switch and i tried wiring it to a different relay but with no wire diagram on how to do it it failed. So i attached the factory blue cable to it because at worse im back to where i started with having no fan running. When running the interior temp guage will say the car is either at 300 or low with no inbetween. Does anyone have a suggetion on what i should do. Should i just go back to factory everything, or does anyone have a good wire diagram or photos of how they wired it up. Or should it just work with the factory wire and there is something else wrong
Your fan comes on at 228
190? Why?
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 25
Likes: 2
I Want it to turn on at 190 because it is my daily driver in the summer and some days in traffic it will get really hot and i dont exactly like that, not very good for wear and tear. And like i said currently the fans dont come on at all so if i can choose when they come on that wpuld be better.
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 25
Likes: 2
The fan is controlled by the ECM. It sounds like you swapped the coolant temp sensor in the cylinder head that sends signal to the temp gauge in your dash, for a temp switch....thinking that would change your fan temps?
I believe that the two ways to get your fan to come on at a lower temp are:
1. reprogram that parameter in the ECM
2. Wire up your own temp switches, relay(s) and run the fan that way.
I believe that the two ways to get your fan to come on at a lower temp are:
1. reprogram that parameter in the ECM
2. Wire up your own temp switches, relay(s) and run the fan that way.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
O.K.
I can help you through that. I've done it on a Trans Am that I installed electric fan(s) on. Do you have one fan? Or two? I'm GUESSING that you simply have the single, one speed fan?
I can help you through that. I've done it on a Trans Am that I installed electric fan(s) on. Do you have one fan? Or two? I'm GUESSING that you simply have the single, one speed fan?
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Thread Starter
Intermediate
Joined: Dec 2021
Posts: 25
Likes: 2
The fan is controlled by the ECM. It sounds like you swapped the coolant temp sensor in the cylinder head that sends signal to the temp gauge in your dash, for a temp switch....thinking that would change your fan temps?
I believe that the two ways to get your fan to come on at a lower temp are:
1. reprogram that parameter in the ECM
2. Wire up your own temp switches, relay(s) and run the fan that way.
I believe that the two ways to get your fan to come on at a lower temp are:
1. reprogram that parameter in the ECM
2. Wire up your own temp switches, relay(s) and run the fan that way.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
O.K. well that's pretty easy. You Need:
*4 or 5 pin relay (doesn't matter which) 35a capacity or so
*40A Maxi fuse and holder (or something similar)
*Wire
*A coolant temp switch spec'd to your on/off preference (closes at, say 200* and opens at 190, for example)
Both of your cylinder heads have two 3/8" pipe thread holes in them. I believe the driver's side already has one of those filled with a sensor or switch...but pick any other available spot and that is where your switch will go. It's nice if you happen to find a temp switch that is the range you want AND the right size pipe thread, but you can use pipe bushings to get other-sized switches to work and the coolant will interface with the switch probe enough to work just dandy.
There are single wire switches and two wire. Sing obviously grounds the pin, to the body. In either case, you can run keyed power to the trigger pins on your relay, then to the switch in the head.... (then to ground if it's a two pin).
Run power from B+, to your maxi fuse, then to the switched side of your relay, then to the B+side of the fan motor.
Remove or stow to the side, the factory fan wiring, and then assemble the above, loom it and secure it properly and you should now have a fan that runs w/in your preferred temp range.
*4 or 5 pin relay (doesn't matter which) 35a capacity or so
*40A Maxi fuse and holder (or something similar)
*Wire
*A coolant temp switch spec'd to your on/off preference (closes at, say 200* and opens at 190, for example)
Both of your cylinder heads have two 3/8" pipe thread holes in them. I believe the driver's side already has one of those filled with a sensor or switch...but pick any other available spot and that is where your switch will go. It's nice if you happen to find a temp switch that is the range you want AND the right size pipe thread, but you can use pipe bushings to get other-sized switches to work and the coolant will interface with the switch probe enough to work just dandy.
There are single wire switches and two wire. Sing obviously grounds the pin, to the body. In either case, you can run keyed power to the trigger pins on your relay, then to the switch in the head.... (then to ground if it's a two pin).
Run power from B+, to your maxi fuse, then to the switched side of your relay, then to the B+side of the fan motor.
Remove or stow to the side, the factory fan wiring, and then assemble the above, loom it and secure it properly and you should now have a fan that runs w/in your preferred temp range.
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 25
Likes: 2
O.K. well that's pretty easy. You Need:
*4 or 5 pin relay (doesn't matter which) 35a capacity or so
*40A Maxi fuse and holder (or something similar)
*Wire
*A coolant temp switch spec'd to your on/off preference (closes at, say 200* and opens at 190, for example)
Both of your cylinder heads have two 3/8" pipe thread holes in them. I believe the driver's side already has one of those filled with a sensor or switch...but pick any other available spot and that is where your switch will go. It's nice if you happen to find a temp switch that is the range you want AND the right size pipe thread, but you can use pipe bushings to get other-sized switches to work and the coolant will interface with the switch probe enough to work just dandy.
There are single wire switches and two wire. Sing obviously grounds the pin, to the body. In either case, you can run keyed power to the trigger pins on your relay, then to the switch in the head.... (then to ground if it's a two pin).
Run power from B+, to your maxi fuse, then to the switched side of your relay, then to the B+side of the fan motor.
Remove or stow to the side, the factory fan wiring, and then assemble the above, loom it and secure it properly and you should now have a fan that runs w/in your preferred temp range.
*4 or 5 pin relay (doesn't matter which) 35a capacity or so
*40A Maxi fuse and holder (or something similar)
*Wire
*A coolant temp switch spec'd to your on/off preference (closes at, say 200* and opens at 190, for example)
Both of your cylinder heads have two 3/8" pipe thread holes in them. I believe the driver's side already has one of those filled with a sensor or switch...but pick any other available spot and that is where your switch will go. It's nice if you happen to find a temp switch that is the range you want AND the right size pipe thread, but you can use pipe bushings to get other-sized switches to work and the coolant will interface with the switch probe enough to work just dandy.
There are single wire switches and two wire. Sing obviously grounds the pin, to the body. In either case, you can run keyed power to the trigger pins on your relay, then to the switch in the head.... (then to ground if it's a two pin).
Run power from B+, to your maxi fuse, then to the switched side of your relay, then to the B+side of the fan motor.
Remove or stow to the side, the factory fan wiring, and then assemble the above, loom it and secure it properly and you should now have a fan that runs w/in your preferred temp range.