fan fuses blowing out
03-25-2006, 03:45 AM
#1
fan fuses blowing out
hello from Germany ,
had something strange happen and was hoping to get some opinions..I have a 1993 LT1 coupe, automatic.
I installed my new Dewitt radiator and it went it nicely with no probs..and flushed the system and bled it. When I did the cutting of the fan shroud, I cut the shroud off my wrecked 92 and installed it, along with the fans from my 92. this shroud has been sitting in my garage since 2002 but never got wet or in the snow..etc.
while doing to engine on/off during the bleed I noticed both my electric fans did not come on..not even when I turned on the AC.
I got a voltmeter out and tested the connectors, and they were both putting out 14V!! I thought that the fans might have gone bad, but for a last try I plugged both connectors in (with the AC running) and they BOTH went on! however the secondary fan died after 10 seconds..and upon testing the connector, it was not putting out any voltage.
now after reading some posts on the forum, I tried splicing the hot wire from the primary fan to the secondary fan since I wanted BOTH fans on at all times anyways...and when I fired it up...both fans were dead with no voltage from the meter from the connectors.
at this point I pulled out my helms manual and began following the troubleshooting guide..
and found that the 40 amp and 30 AMP fuses that are located in a box near the battery had both blown out. I replaced to 40 AMP primary (since the primary was driving both fans now) and both fans came to life..I test drove for 10 minutes..and the car ran great and very cool (Im sure the dewitt had alot to do with that too). pulled it back into the shop and gave a thumbs up to the guys helping me out...and then the temp spiked to 212 and rising...stopped the car ..both fans dead. and the 40A fuse was blown.
Ill rewire everything again to original and put new fuses in...
but does anyone have any idea why the secondary blew its fuse in the 1st place..and could powering two fans possibly have blown the primary fuse?
and could it be the fans drawing so much that they blew a fuse? I doubted that a pair of fans sitting for 4 years could "bind" but I dont know ....
had something strange happen and was hoping to get some opinions..I have a 1993 LT1 coupe, automatic.
I installed my new Dewitt radiator and it went it nicely with no probs..and flushed the system and bled it. When I did the cutting of the fan shroud, I cut the shroud off my wrecked 92 and installed it, along with the fans from my 92. this shroud has been sitting in my garage since 2002 but never got wet or in the snow..etc.
while doing to engine on/off during the bleed I noticed both my electric fans did not come on..not even when I turned on the AC.
I got a voltmeter out and tested the connectors, and they were both putting out 14V!! I thought that the fans might have gone bad, but for a last try I plugged both connectors in (with the AC running) and they BOTH went on! however the secondary fan died after 10 seconds..and upon testing the connector, it was not putting out any voltage.
now after reading some posts on the forum, I tried splicing the hot wire from the primary fan to the secondary fan since I wanted BOTH fans on at all times anyways...and when I fired it up...both fans were dead with no voltage from the meter from the connectors.
at this point I pulled out my helms manual and began following the troubleshooting guide..
and found that the 40 amp and 30 AMP fuses that are located in a box near the battery had both blown out. I replaced to 40 AMP primary (since the primary was driving both fans now) and both fans came to life..I test drove for 10 minutes..and the car ran great and very cool (Im sure the dewitt had alot to do with that too). pulled it back into the shop and gave a thumbs up to the guys helping me out...and then the temp spiked to 212 and rising...stopped the car ..both fans dead. and the 40A fuse was blown.
Ill rewire everything again to original and put new fuses in...
but does anyone have any idea why the secondary blew its fuse in the 1st place..and could powering two fans possibly have blown the primary fuse?
and could it be the fans drawing so much that they blew a fuse? I doubted that a pair of fans sitting for 4 years could "bind" but I dont know ....
03-25-2006, 10:39 AM
#2
Team Owner
Member Since: Mar 2001
Location: Cincinnati, Oh USA
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Two fan motors cannot be run on a fuse meant for one fan motor. The running current exceeds the fuse rating. Each fan motor has its own fuse for this reason. Fuses sized for two fan motors are not made in the physical size used in the vette because the fuse clips cannot safely carry that much current. I would measure the running current of each fan motor and see if they are normal, it sounds like they are not! My fan in my 87 draws 14 amps and the only trouble I have ever had is the fan motor stopped running and had to be replaced.
03-25-2006, 12:17 PM
#3
I went back to the shop today and wired things back to normal with each fan getting its own power...and the secondary fan blew its fuse every time. Stranger yet, the primary fan stopped running at one point. In a 1993, doesn't the primary fan always stay on? or is it temperature activated? in any case I pulled out both fans and put my original fans back on, and snipped the wire that sends the control signal from the ECM to the fan to turn it off or on...and spliced it with the secondary fans control signal so it would mimic what the primary was doing. Now both fans turn on and off at the same time...when I start up the motor both fans turn on...then after a few minutes they shut off...the engine remains at about 194 F at this point. AT any point, if I turn on the A/C both fans kick on. I havent taken it out for a drive yet to see at what temp the primary will kick on (which in this case would also turn on the secondary). Does anyone know if the primary is supposed to always be on or what conditions will have it turn off? thanks
03-25-2006, 03:41 PM
#4
Le Mans Master
Non a/c, PCM grounds the Primary Relay at 217 or 219 and the secondary at 226 - 228. Signal is from the Coolant Temp Sensor and no, the fan(s) is/are not running all the time - they turn off below these temps - UNLESS, the A/C is on - then the PCM grounds both relays when the voltage at the Pressure Sensor indicates 150 psi (about 1.5 volts and a refrigerant temp of about 120 degrees). A fully charged system should see that on the high side allmost any time it's above 50 degrees, so it might seem as if the fans are always on when a/c is selected. That's also why your car should run cooler with the a/c on - refrigerant has to be cooled below the thermostat for it to operate properly. PCM won't ground the relays if speed is above 35 to 40 mph - hard to tell what they're doing when you're driving it of course.
If your secondary fuse is blowing and the wiring is good, you need a new motor.
If your secondary fuse is blowing and the wiring is good, you need a new motor.
03-25-2006, 03:50 PM
#5
Team Owner
Member Since: Mar 2001
Location: Cincinnati, Oh USA
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If the 93 is like the earlier C4's, the main fan comes on at 228 F, and the auxilliary fan at 238 F. If the a/c freon line pressure exceeds 240 psi (usually caused by turning on the compressor), the a/c coolant fan switch closes and causes the main fan to come on. Measure the fan motor current, I am sure it exceeds the fuse rating.
