Fan question, No response in the cooling board
#1
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Car: 1992 Camaro Z28 Convertible Z03
Engine: 383 SuperRam
Transmission: 700R4
Axle/Gears: 2.73
Fan question, No response in the cooling board
Yesterday I started to check into why my fans weren't working. Its a 91Z 305 TPI with the dual fans.
First: I jumpered the big wires in the relay plug. Fans worked.
Second: I plugged the relay in, stripped away some wire casing on the green/white wire and used a jumper to ground it. Fans Worked
Third: I started it made sure I was up to temp. No Fans
Fourth: While running I tried various A/C and defrost settings. No Fans
Fifth: I jumpered A and B on the ALDL port. Fans WORKED.
So after all that I know the wiring is good and the relay is good. I thought when the a/c or defrost are on it doesn't use the temp sensor so that would rule that out. Am I correct?
Does this narrow it down to the ECM or could it still be the temp sensor. Or what else could it be?
Thanks
First: I jumpered the big wires in the relay plug. Fans worked.
Second: I plugged the relay in, stripped away some wire casing on the green/white wire and used a jumper to ground it. Fans Worked
Third: I started it made sure I was up to temp. No Fans
Fourth: While running I tried various A/C and defrost settings. No Fans
Fifth: I jumpered A and B on the ALDL port. Fans WORKED.
So after all that I know the wiring is good and the relay is good. I thought when the a/c or defrost are on it doesn't use the temp sensor so that would rule that out. Am I correct?
Does this narrow it down to the ECM or could it still be the temp sensor. Or what else could it be?
Thanks
#2
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Car: 86 IROC
Engine: 350 Vortec TPI
Transmission: 700R4
Axle/Gears: BW 3.27
Re: Fan question, No response in the cooling board
Dual fans work independently of each other. One fan will kick in when the motor is to temp and the other is based off of a/c line pressure. So you may have two separate issues. There will be inlines fuses for the relays as well as fuel and ecm. They should be on the inside fender of the passanger side where the battery is. Check those.
On the passanger side frame rail, you will see the liquid line that goes from the evap to condensor. On the line you will see a pressure sensor with a blue/white or grey and a black wire. with the car running or in the On position, if you jump those wires I believe the passenger side fan will kick in. If it does its the pressure sensor.
The driver side is controlled by the ECM when it reaches temp. If you have the ability to put a scanner on the car, you will see if the temp sensor is working or not....
On the passanger side frame rail, you will see the liquid line that goes from the evap to condensor. On the line you will see a pressure sensor with a blue/white or grey and a black wire. with the car running or in the On position, if you jump those wires I believe the passenger side fan will kick in. If it does its the pressure sensor.
The driver side is controlled by the ECM when it reaches temp. If you have the ability to put a scanner on the car, you will see if the temp sensor is working or not....
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Re: Fan question, No response in the cooling board
The primary fan is controls the fan relays ground side when the coolant temperature (cts) reaches 226F the ecm will ground the coil in fan relay.
The secondary fan is turned on then the coolant temp sensor if equipted is grounded or the a/c pressure switch is closed.
The secondary fan is turned on then the coolant temp sensor if equipted is grounded or the a/c pressure switch is closed.
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: Fan question, No response in the cooling board
Looking more like a input problem to the ECM so it is not getting the trigger to operate the fans?
#5
Re: Fan question, No response in the cooling board
Its likely the sensor.
The other fan will come on when the AC is turned on AND BUILDS PRESSURE. In the case of my car, it never came on. This fan also turns on when temps get HOT, IMO too late to do any good, you've already noticed it was way too hot and have shut the car off waiting for it to cool down.
The other fan will come on when the AC is turned on AND BUILDS PRESSURE. In the case of my car, it never came on. This fan also turns on when temps get HOT, IMO too late to do any good, you've already noticed it was way too hot and have shut the car off waiting for it to cool down.
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Car: 1992 Camaro Z28 Convertible Z03
Engine: 383 SuperRam
Transmission: 700R4
Axle/Gears: 2.73
Re: Fan question, No response in the cooling board
I changed the sensor today and still no fan. This is getting frustrating. Any other ideas?
#7
Re: Fan question, No response in the cooling board
To the OP, if you have the ability to datalog, check and see what the ECM is seeing for engine temps.
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#8
Re: Fan question, No response in the cooling board
By RBob from the EBL thread:
> 2. Fan1 flag comes on in the WUD, Fan1 stays off in the engine compartment.
This one doesn't sound good. Since it works when in limp mode but not when commanded by the ECM, I'd say that the ECM went bad. The limp mode operation of the fan is the last gate before the driver. With the ECM control over the fan being further upstream of this gate.
This one doesn't sound good. Since it works when in limp mode but not when commanded by the ECM, I'd say that the ECM went bad. The limp mode operation of the fan is the last gate before the driver. With the ECM control over the fan being further upstream of this gate.
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Car: 1989 Firebird Formula
Engine: 385
Transmission: Full Manual TH350
Axle/Gears: Moser 9" 3.70
Re: Fan question, No response in the cooling board
Is it a custom tune? Is there ANY chance at all that the fan turn on temps were raised in the ecm?
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Re: Fan question, No response in the cooling board
I remember reading that the stock ecm was programed to kick the fan on at 238 degrees or something high like that. Are you checking the fan sensor on the passenger side head under the manifold?
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Car: 1992 Camaro Z28 Convertible Z03
Engine: 383 SuperRam
Transmission: 700R4
Axle/Gears: 2.73
Re: Fan question, No response in the cooling board
A lot of attention has been put into keeping the car original. Even when new shocks were put on they were Ac Delco's so I doubt the tune has been messed with. I am checking the correct sensor. I replaced it today with an AC Delco one.
I just ordered another ECM off eBay to hopefully fix it.
Off topic question. My Speedo doesnt work either. Its not the VSS. I thought it was and replaced it and got back my odometer, but not speedometer. Could a bad ECM kill the speedo too or should I just concede the fact I need a cluster too.
I just ordered another ECM off eBay to hopefully fix it.
Off topic question. My Speedo doesnt work either. Its not the VSS. I thought it was and replaced it and got back my odometer, but not speedometer. Could a bad ECM kill the speedo too or should I just concede the fact I need a cluster too.
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