cooling fans operating range
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Joined: Mar 2004
Posts: 97
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From: Sanford FL
cooling fans operating range
I read several threads regarding the cooling fans operation. Mine seem to be operating within factory specs according to the digital instrument. The digital temp reading shows the fans come on at 228 degrees and turn off at 217 degrees. I've watched it cycled several times to make sure it was consistence. However the analog gauge reads different. The analog shows the fans kick on about 255 degree, close to the warning area by 260 degree. We have a digital temp sensor tool that reads the actual temperatures when placing on the radiator hoses and it reads close to what the digital reading are. Why is the analog not the same as the digital? Is the analog gauge going bad? Can it be reset, adjusted, etc...? I appreciate any input on this issue.
Instructor
Joined: Jun 2014
Posts: 129
Likes: 3
From: Atlanta area Georgia
temperature
I read several threads regarding the cooling fans operation. Mine seem to be operating within factory specs according to the digital instrument. The digital temp reading shows the fans come on at 228 degrees and turn off at 217 degrees. I've watched it cycled several times to make sure it was consistence. However the analog gauge reads different. The analog shows the fans kick on about 255 degree, close to the warning area by 260 degree. We have a digital temp sensor tool that reads the actual temperatures when placing on the radiator hoses and it reads close to what the digital reading are. Why is the analog not the same as the digital? Is the analog gauge going bad? Can it be reset, adjusted, etc...? I appreciate any input on this issue.
I was told that the first fan kicked on at 128 and the second at 236
unless you have the air on. These temperatures drove me nuts.
I watched the gauges more than the road.
Talked to several people, and I replace the thermostat with a 160
degree one. And bought the hyperteck system. I have a 96 with
obd2
Now instead of running between 125 and 132, I am running between
180 and 190. It gave me a lot of peace of mind. Not sure of your
year so may require a different program.
If you decide on the hypertech, they are pricey, right around
$400.00 plus shipping. Found the system on either ebay or amazon.
To make a long story short, it was shipped from JEGS with no
shipping charge for $329.00 Still pricy in my book.
Didn't really answer your question about the difference between the
analog and digital. I prefer digital and pretty mush ignore the analog.
BUT I COULD BE WRONG. Just wanted to the little bit I have learned.
Preacher Putz
The hypertech
Instructor
Joined: Jun 2014
Posts: 129
Likes: 3
From: Atlanta area Georgia
[QUOTE=preacher putz;1588319140]I am new at this, but I have had a lot of help from our senior members.
I was told that the first fan kicked on at 128 and the second at 236
unless you have the air on. These temperatures drove me nuts.
I watched the gauges more than the road.
Talked to several people, and I replace the thermostat with a 160
degree one. And bought the hyperteck system. I have a 96 with
obd2
Now instead of running between 125 and 132, I am running between
180 and 190. It gave me a lot of peace of mind. Not sure of your
year so may require a different program.
If you decide on the hypertech, they are pricey, right around
$400.00 plus shipping. Found the system on either ebay or amazon.
To make a long story short, it was shipped from JEGS with no
shipping charge for $329.00 Still pricy in my book. But I sleep
better at night.
Didn't really answer your question about the difference between the
analog and digital. I prefer digital and pretty mush ignore the analog.
BUT I COULD BE WRONG. Just wanted to share the little bit I have learned.
Preacher Putz
I was told that the first fan kicked on at 128 and the second at 236
unless you have the air on. These temperatures drove me nuts.
I watched the gauges more than the road.
Talked to several people, and I replace the thermostat with a 160
degree one. And bought the hyperteck system. I have a 96 with
obd2
Now instead of running between 125 and 132, I am running between
180 and 190. It gave me a lot of peace of mind. Not sure of your
year so may require a different program.
If you decide on the hypertech, they are pricey, right around
$400.00 plus shipping. Found the system on either ebay or amazon.
To make a long story short, it was shipped from JEGS with no
shipping charge for $329.00 Still pricy in my book. But I sleep
better at night.
Didn't really answer your question about the difference between the
analog and digital. I prefer digital and pretty mush ignore the analog.
BUT I COULD BE WRONG. Just wanted to share the little bit I have learned.
Preacher Putz
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
your year would help...but sounds like you're running too hot.....do not buy a hypertech chip....worthless.....they will turn your fan or fans earlier but a simple manual switch does it too....there are many threads regarding this....clean the radiator and spaces out, put in a 160 t stat and a manual switch....that should do it, although older c4's could us a new radiator(and better one)... my hypertech chips sits in a box in my garage to remind me how stupid i can be....it does not add power.....you can buy a manual switch a ecklers for 16 bucks.....or go to ace 5 bucks...
Race Director
Joined: Oct 2005
Posts: 11,769
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
I read several threads regarding the cooling fans operation. Mine seem to be operating within factory specs according to the digital instrument. The digital temp reading shows the fans come on at 228 degrees and turn off at 217 degrees. I've watched it cycled several times to make sure it was consistence. However the analog gauge reads different. The analog shows the fans kick on about 255 degree, close to the warning area by 260 degree. We have a digital temp sensor tool that reads the actual temperatures when placing on the radiator hoses and it reads close to what the digital reading are. Why is the analog not the same as the digital? Is the analog gauge going bad? Can it be reset, adjusted, etc...? I appreciate any input on this issue.
The biggest difference though, is the fact that analog gauge really isn't very accurate to begin with.
The scale is not linear, so it is very hard to tell what temp the needle is actually pointing too.
Always go by the digital temp gauge.
You will probably notice that when your digital reading is in the 225°F - 230°F range, that analog gauge needle will be very close (but not quite into) the shaded area on your analog gauge.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Your temps are just fine.
217°-228° [Digital] while idling are FSM values. Your Analog gauge reads cylinder head temperature, and this is were most of the heat is generated.
Although most say it's not accurate, I believe it is! it's just not read on an Linear Scale.. don't confuse Linearity, and accuracy. They have different definitions.
The Cylinder Heads run hot enough to generate steam i.e. 255°-265° this is why GM installed steam [Vent] pipes at the back of the heads in order to Mitigate gas build up in the heads.
Now the real important Question is what are your temps while cruising? if they climb above, say 210°-215° then I would say your running a bit Hot..
217°-228° [Digital] while idling are FSM values. Your Analog gauge reads cylinder head temperature, and this is were most of the heat is generated.
Although most say it's not accurate, I believe it is! it's just not read on an Linear Scale.. don't confuse Linearity, and accuracy. They have different definitions.
The Cylinder Heads run hot enough to generate steam i.e. 255°-265° this is why GM installed steam [Vent] pipes at the back of the heads in order to Mitigate gas build up in the heads.
Now the real important Question is what are your temps while cruising? if they climb above, say 210°-215° then I would say your running a bit Hot..
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Your temps are just fine.
217°-228° [Digital] while idling are FSM values. Your Analog gauge reads cylinder head temperature, and this is were most of the heat is generated.
Although most say it's not accurate, I believe it is! it's just not read on an Linear Scale.. don't confuse Linearity, and accuracy. They have different definitions.
The Cylinder Heads run hot enough to generate steam i.e. 255°-265° this is why GM installed steam [Vent] pipes at the back of the heads in order to Mitigate gas build up in the heads.
Now the real important Question is what are your temps while cruising? if they climb above, say 210°-215° then I would say your running a bit Hot..
217°-228° [Digital] while idling are FSM values. Your Analog gauge reads cylinder head temperature, and this is were most of the heat is generated.
Although most say it's not accurate, I believe it is! it's just not read on an Linear Scale.. don't confuse Linearity, and accuracy. They have different definitions.
The Cylinder Heads run hot enough to generate steam i.e. 255°-265° this is why GM installed steam [Vent] pipes at the back of the heads in order to Mitigate gas build up in the heads.
Now the real important Question is what are your temps while cruising? if they climb above, say 210°-215° then I would say your running a bit Hot..
In reading the first post closely, it states the "fans" come on at…. So sounds line he is talking about 2 fans coming on at 228* which would make it a 95 or 96. Having the year would sure take out the guess work out to answer a question with best accuracy.
You can always replace the analog temp sensor in the side of the block to get better accuracy. It's a shot and it may or may not help but other than that the analog gauge just has some age on it and I would just leave it alone at that point. (I feel lucky mine tracks pretty good on my 94).
Installation of a manual switch is different for a 94 and earlier, and a 95 and up. As I have one and really need it in Orlando.
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Racer
Joined: Jun 2014
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From: Mesa AZ
I have an 88 verte. and my fan comes on @228 degrees. The analog is close however if you are running at 260, you are running HOT! Shut your a/c off if it's on and turn the heater on if you can stand it and then watch your temp gauge. Although I did re-read his thread and he said "fans" whereas I have one. I talked to Rick Hendrick's Corvette specialist at Kansas City and he said that 250 is acceptable but more than that, you should pull over and let it cool. I have had mine up to 238 and C4inMesa has had his up to 245+ but his is an 87 I believe. I would drain your system, flush and clean and then add some Water Wetter and see how your temps run. A 160 thermostat will not help. I live in Az and run a 195 and it doesn't take long to get there. Cruising speed @70 mph the temp drops to around 200-205. Make sure you have the right rad cap and the overflow is good and clean after you flush.
Tommy
Tommy
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My 95 runs the fans as posted above fan 1 around 225 fan 2 around 235, If I'm not mistaken it changed in 96 OBD2 with both fans running in a low speed and hi speed state controlled by the computer, of coarse the AC also has some control of the fans. You should also have a 195 thermostat that should make your moving or road temps around 200-215 dependent on outside temp.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
My 95 runs the fans as posted above fan 1 around 225 fan 2 around 235, If I'm not mistaken it changed in 96 OBD2 with both fans running in a low speed and hi speed state controlled by the computer, of coarse the AC also has some control of the fans. You should also have a 195 thermostat that should make your moving or road temps around 200-215 dependent on outside temp.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
My 95 runs the fans as posted above fan 1 around 225 fan 2 around 235, If I'm not mistaken it changed in 96 OBD2 with both fans running in a low speed and hi speed state controlled by the computer, of coarse the AC also has some control of the fans. You should also have a 195 thermostat that should make your moving or road temps around 200-215 dependent on outside temp.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
I thought all 95s had the 3 relay fan setup. But 95 was a transition year for several items of which fans were one of them. It is very possible that depending on the month of manufacture, some 95s could have the 2 or the 3 relay fan set up. Seems like that may be the case here.
Learn something new everyday..
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Mine definitely turns on fan #1 left side at 228 and than fan #2 right side at 238. Have checked it many time over the 200k miles I put on it. Just replaced fan 2 motor last year the LT1 is an early production #228. Both my ZR-1's have modded prom to turn both on at 210 and off at 200.
Last edited by FASTAZU; Nov 24, 2014 at 03:48 PM.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Mine definitely turns on fan #1 left side at 228 and than fan #2 right side at 238. Have checked it many time over the 200k miles I put on it. Just replaced fan 2 motor last year the LT1 is an early production #228. Both my ZR-1's have modded prom to turn both on at 210 and off at 200.
