99 Corvette Coolant Fan issue
11-29-2016, 12:05 PM
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Heel & Toe
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99 Corvette Coolant Fan issue
Hey Everyone,
Bought a neglected 1999 Chevy Corvette and am giving her lots of TLC.. Be brand new by the time im done. lol..
Back in 2014 the owner had a cooling issue so they brought it to a shop and had a new coolant system put in..
My question is.. when i start the car it smells hot.. I know Corvettes run hot looking at the temp lights the coolant gets to around 210 and I think the oil is at like 175 if i remember right. I never hear the fans kick on. But the car has never overheated. I ran it last night in my driveway for about 20 minutes and no fans turned on.. All temps were in normal range.
I checked the relays and they all tested good. I cant check the fans with the AC on cause the previous owner removed parts of it..
I know through research if the car doesnt get to 230 then the fans dont turn on.. not sure if the coolant system that they put in.. is working correctly or if the temperature sensor is giving a false reading..
Any help is greatly appreciated.
Greg
Bought a neglected 1999 Chevy Corvette and am giving her lots of TLC.. Be brand new by the time im done. lol..
Back in 2014 the owner had a cooling issue so they brought it to a shop and had a new coolant system put in..
My question is.. when i start the car it smells hot.. I know Corvettes run hot looking at the temp lights the coolant gets to around 210 and I think the oil is at like 175 if i remember right. I never hear the fans kick on. But the car has never overheated. I ran it last night in my driveway for about 20 minutes and no fans turned on.. All temps were in normal range.
I checked the relays and they all tested good. I cant check the fans with the AC on cause the previous owner removed parts of it..
I know through research if the car doesnt get to 230 then the fans dont turn on.. not sure if the coolant system that they put in.. is working correctly or if the temperature sensor is giving a false reading..
Any help is greatly appreciated.
Greg
11-29-2016, 01:12 PM
#2
mike v
11-29-2016, 01:38 PM
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Heel & Toe
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If you turn on the AC then the cooling fans should turn on at about 185 degrees of coolant temp.
Factory settings for the cooling fans WITHOUT AC is low speed fan operation begins when the coolant temp reaches 226 degrees. When the coolant temp drops to 219 degrees the fans are commanded OFF. If the coolant temp reaches 235 degrees then the cooling fans switch to high speed mode. When the coolant temp drops to 226 degrees the cooling fans revert to low speed mode. BOTH fans should run in both low speed and high speed mode.
Here is the electrical diagram for the cooling fans. As you can see the fans are set in electrical series for low speed operation. So there is approximately 1/2 of battery voltage across each fan motor and hence they run at less than rated speed. When commanded to high speed mode the fans are configured in electrical parallel mode so full battery voltage is across each fan motor. Hence each can run at its rated speed.
GM was apparently concerned about the AC system having issues when it is running and engine temp reached high levels so it designed the cooling fan system to come on in low speed mode at 185 degrees coolant temp.
Also be aware that the fans are commanded OFF when the vehicle speed exceeds 35 MPH IRRESPECTIVE of coolant temp.
This is really the wrong time of year to try and see what the cooling fans are doing UNLESS your cooling system is malfunctioning. From the temps you reported the system is likely operating correctly.........
Factory settings for the cooling fans WITHOUT AC is low speed fan operation begins when the coolant temp reaches 226 degrees. When the coolant temp drops to 219 degrees the fans are commanded OFF. If the coolant temp reaches 235 degrees then the cooling fans switch to high speed mode. When the coolant temp drops to 226 degrees the cooling fans revert to low speed mode. BOTH fans should run in both low speed and high speed mode.
Here is the electrical diagram for the cooling fans. As you can see the fans are set in electrical series for low speed operation. So there is approximately 1/2 of battery voltage across each fan motor and hence they run at less than rated speed. When commanded to high speed mode the fans are configured in electrical parallel mode so full battery voltage is across each fan motor. Hence each can run at its rated speed.
GM was apparently concerned about the AC system having issues when it is running and engine temp reached high levels so it designed the cooling fan system to come on in low speed mode at 185 degrees coolant temp.
Also be aware that the fans are commanded OFF when the vehicle speed exceeds 35 MPH IRRESPECTIVE of coolant temp.
This is really the wrong time of year to try and see what the cooling fans are doing UNLESS your cooling system is malfunctioning. From the temps you reported the system is likely operating correctly.........
Thanks again