Fan stopped working
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Like I said I don't know what is causing it. Your posts were not real clear on the before and after temps when you changed the sensor. That aside, the problem IMO is somewhere in the analog side of your readings. I would start trouble shooting there and see what you find. It could be the new sensor, I have no way to know. As you may know many C4's like my 1989 have no analog gauge and we get along just fine.
Last edited by BADDUCK; Nov 24, 2009 at 10:13 AM.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
BTW, thanks for the help. Right or wrong discussion is what helps us.[/QUOTE]
Replace sensor that is on side of block with a A/C DELCO brand part.If this does not "fix" anolog gauge you may have a problem with your wiring or have a bad instrument cluster(temp anolog),just keep an eye on the digital gauge since this is what your computer is seeing.Do not replace sensor on waterpump since it is operating properly.If you do replace this sensor make sure you bleed cooling system properly or you WILL have overheating issues.BTW may anolog gauge on my 94 reads high but my digital gauge reads properly.The anolog gauge is inaccurate on almost all cars.I've had customers bring their car to me because their anolog gauge gets close to hot.I check the actual temp the computer is seeing & everything is working fine so I tell them the same thing-anolog gauge is a "dummy" gauge is not accurate.
Replace sensor that is on side of block with a A/C DELCO brand part.If this does not "fix" anolog gauge you may have a problem with your wiring or have a bad instrument cluster(temp anolog),just keep an eye on the digital gauge since this is what your computer is seeing.Do not replace sensor on waterpump since it is operating properly.If you do replace this sensor make sure you bleed cooling system properly or you WILL have overheating issues.BTW may anolog gauge on my 94 reads high but my digital gauge reads properly.The anolog gauge is inaccurate on almost all cars.I've had customers bring their car to me because their anolog gauge gets close to hot.I check the actual temp the computer is seeing & everything is working fine so I tell them the same thing-anolog gauge is a "dummy" gauge is not accurate.
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
You say you had to take the first sensor back because it didn't fit. The second one fit but was called a switch and produced a suspect reading. It is not a switch but a thermister. A resistor that varies in resistance with temp.
Right now you have two temp readings with no definite way to say which is correct. Common sense says that the one you last replaced is the likely suspect but you cannot be sure without proof.
Do you have an IR thermometer? You could use that to narrow it down.
If it were me, I would try a new sensor from a different supplier.
Right now you have two temp readings with no definite way to say which is correct. Common sense says that the one you last replaced is the likely suspect but you cannot be sure without proof.
Do you have an IR thermometer? You could use that to narrow it down.
If it were me, I would try a new sensor from a different supplier.
When I was installing my headers I broke a sensor on the pass side of the block just between and below 3rd and 4th cylinders. I bought the "coolant temp sensor" only to find out it wouldn't plug in so then I had to buy the "coolant temp switch". It fit perfect and my temp gauge is working again.
Last edited by MK 82; Nov 24, 2009 at 11:27 AM.
Thread Starter
Melting Slicks
Joined: Feb 2009
Posts: 2,072
Likes: 1
From: Oklahoma City OK
St. Jude '10
This is what I bought the 2nd time and it fit just as it was supposed to. Autozone calls it a temp switch.
http://www.autozone.com/autozone/cat...xt=temp+switch
http://www.autozone.com/autozone/cat...xt=temp+switch
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
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Cruising
Joined: Dec 2009
Posts: 11
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fan not working
When I was installing my headers I broke a sensor on the pass side of the block just between and below 3rd and 4th cylinders. I bought the "coolant temp sensor" only to find out it wouldn't plug in so then I had to buy the "coolant temp switch". It fit perfect and my temp gauge is working again. The fan wasn't coming on so I took it for a run and thought all was well but When I got back and let the car idle still no fan even up to 250 degrees. Anyone know what would cause the fan not come on? It works fine in AC mode so it's not the fan motors.
Thread Starter
Melting Slicks
Joined: Feb 2009
Posts: 2,072
Likes: 1
From: Oklahoma City OK
St. Jude '10
When I turn off the AC/Heater it does the same thing if I understand you correctly. It kills the auto fan. When I do this the temp goes through the roof before the fan comes on. I bought new BETTER sending units (both). I just haven't put them in yet. I did notice the other day when it was 10* outside the heater wouldn't warm the car. So either the engine wasn't getting to temp or the heater core is blocked. I know there are a lot of other variables like vent controls and thermostat working or not. It's just too cold to work on it now.
Racer
Joined: Aug 2006
Posts: 403
Likes: 0
From: Huntsville Alabama
When I turn off the AC/Heater it does the same thing if I understand you correctly. It kills the auto fan. When I do this the temp goes through the roof before the fan comes on. I bought new BETTER sending units (both). I just haven't put them in yet. I did notice the other day when it was 10* outside the heater wouldn't warm the car. So either the engine wasn't getting to temp or the heater core is blocked. I know there are a lot of other variables like vent controls and thermostat working or not. It's just too cold to work on it now.
Thread Starter
Melting Slicks
Joined: Feb 2009
Posts: 2,072
Likes: 1
From: Oklahoma City OK
St. Jude '10
If I remember correctly (it's been a while, this thread is a couple months old) I was getting about 228 on the digital and 255 almost pegged on the analog. Somewhere I posted on this thread these results. Did you recently replace one of your sensors as I did?
Racer
Joined: Aug 2006
Posts: 403
Likes: 0
From: Huntsville Alabama
I replaced my water pump sensor last year. It did not make a change. Last night I did a trial on my 96 LT1. I let the car run idle while monitoring the temperature gauges. My fans did turn on low speed around 230*ish and my analog gauge was on the hash mark before the 265* mark. I may be wrong but there is a strong possibility that my sensor for the analog gauge may be flakey. Looking in the FSM to see if there is a test for the block temperature sensor. It's cheap to purchase but a pain to replace. There is similiar recent post in the C4 general discussion. I think RollaMo is on the button with his post.
