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-   -   Radiator Fan/relay (http://www.clubcobra.com/forums/all-cobra-talk/101745-radiator-fan-relay.html)

psychoSEAL 12-29-2009 08:18 AM
Radiator Fan/relay
 
Over the past few weeks I posted a problem with my fan relay. The wiring has been in place for almost 2 years and no problems. I uncovered a blown inline fuse (no big deal) replaced and the fan started working again. Until the next time I drove the car and smelled something like an electrical burning smell. Thus, finding the inline fuse holder melted. The relay wiring is from SPAL with a 30 amp fuse and a 40 amp relay. I also had it wired to where I could manually turn the fan on if ever needed. The fan is from a 89-95 3.8L Ford Taurus that I wired to the high speed fan and not utilizing the low speed. After reading a number of post on this site and a few other sites, I uncovered the fact that a Taurus 3.8L fan puts out around 4500cfm and requiring a higher amperage relay. Now, after 2 years do you think this is the problem with my blown/burnt fuse and fuse holder? Should I switch the setup to where I am not using the high speed fan and go with the low speed? Do I go with a higher amp relay? I like keeping things simple with the wiring because I am not an electrical magician by no means. Ideas? Thanks!!

undy 12-29-2009 08:45 AM
Quote:
Originally Posted by psychoSEAL (Post 1013477)
Over the past few weeks I posted a problem with my fan relay. The wiring has been in place for almost 2 years and no problems. I uncovered a blown inline fuse (no big deal) replaced and the fan started working again. Until the next time I drove the car and smelled something like an electrical burning smell. Thus, finding the inline fuse holder melted. The relay wiring is from SPAL with a 30 amp fuse and a 40 amp relay. I also had it wired to where I could manually turn the fan on if ever needed. The fan is from a 89-95 3.8L Ford Taurus that I wired to the high speed fan and not utilizing the low speed. After reading a number of post on this site and a few other sites, I uncovered the fact that a Taurus 3.8L fan puts out around 4500cfm and requiring a higher amperage relay. Now, after 2 years do you think this is the problem with my blown/burnt fuse and fuse holder? Should I switch the setup to where I am not using the high speed fan and go with the low speed? Do I go with a higher amp relay? I like keeping things simple with the wiring because I am not an electrical magician by no means. Ideas? Thanks!!
Your relay, fuse and probably the wiring is undersized for the Taurus fan. You need a 50 amp fuse and a 60 to 70 amp relay. Wiring should be #8. You've just been lucky thus far and it finally caught up with you. I'm running the Taurus setup myself..

Wbulk 12-29-2009 09:32 AM
One question that comes to mind is why was the inline fuse holder melted. Usually, but now always, the wiring for an inline fuse is not large enough to handle an electric fan where the wiring is often a 8 or 10 gauge wire. Was the 30 amp fuse the one that was burnt.
A relay allows a low current to switch a higher current, and on a good system will have a fuse on the low side and the high current side before the relay. The 40 amp relay only means that it can handle up to 40 amps flowing through it with the correct size wiring and fuses. You can run a smaller fuse as long as the curent draw is not greater than the fuse you are using.
One thing you might look at is take an ohm meter and connect from the battery side of the burnt fuse and the other side to where that wire leads and stating wiggling that wire from one end to the other. Inline fuses if not supported can cause the wire to fray inside the insulation from vibration, which is like running a smaller wire that would blow the fuse when the fan turns on. If this is the cause you may see the resistance (ohms) get higher if you happen to wiggle the area where a wired is frayed in the insulation. On the other hand your fan could just be going.
Keep us posted as you find things out.
Good luck.
Wayne

psychoSEAL 12-29-2009 09:44 AM
WBulk, Yes the burnt fuse was a 30 amp. The entire fuse holder was melted. In fact the fuse crumbled to the floor when I got the the fuse holder open. I was thinking about replacing the inline fuse holder and the relay. This car has a 351w and no special bells and whistles so I am thinking that by using a lower cfm rated fan such as the low speed on this particular fan while replacing the relay and fuse/fuse holder this might solve the problem. Thanks!!

psychoSEAL 12-29-2009 09:48 AM
Undy, That's what was wondering. If I go to a higher amp fuse and relay, will this require me to do anything to my current wiring? I thought maybe just doing away with the manual switch that I never used anyway and going with the relay/temp sender. Where can you find the higher amp fuse/relay setup? Thanks!!

Wbulk 12-29-2009 09:57 AM
Good place to start. Like undy said, check your wiring size while you are at it.

psychoSEAL 12-30-2009 11:43 AM
After a good conversation with Blas and your replies concerning my fan. I have come to the conclusion that this fan, while in the high speed is just to much to handle on my current system. The 40/50 amp relay and the 30 amp fuse is just not enough. After doing some research I found that a Taurus 3.8L fan can produce approx 4000 cfm while drawing around 45 amps. At the low speed a good 2500 cfm and 25 amps. So before I go out and change the entire fan/radiator/wiring I am going to replace the relay and the inline fuse while wiring to the low speed setting. This should be ample enough cfm to cool this motor. I'll keep you informed of my progress. Thanks!

undy 12-30-2009 04:10 PM
Quote:
Originally Posted by psychoSEAL (Post 1013787)
After a good conversation with Blas and your replies concerning my fan. I have come to the conclusion that this fan, while in the high speed is just to much to handle on my current system. The 40/50 amp relay and the 30 amp fuse is just not enough. After doing some research I found that a Taurus 3.8L fan can produce approx 4000 cfm while drawing around 45 amps. At the low speed a good 2500 cfm and 25 amps. So before I go out and change the entire fan/radiator/wiring I am going to replace the relay and the inline fuse while wiring to the low speed setting. This should be ample enough cfm to cool this motor. I'll keep you informed of my progress. Thanks!
Hollister makes a trick relay/wiring harness expressly for the Taurus and the MK 8 fans. That's what I'm running. You can order it with 180 and a 195 sensors so it will stage both speeds, low speed on @ 180 and hi speed comes on/low speed shuts off at 195. It comes with enough "right sized" wiring to (more than likely) reach your buss bar/fuse block.

http://www.hollisterroad.com/

BTW... Make sure your alternator and main wiring is up to the task too.. (a minimum of a 100 amp alternator is required, 140 more advisable)

Dave

psychoSEAL 12-31-2009 06:48 PM
Undy, That's another issue. This alternator is putting out 60 amps. I thought it was a 100 amps but had it tested by a few shops and 60 amps is more like it. This and not having enough amps in the fuse and relay with a fan that pulled to much amps and you have the problem that I have. Thanks for the idea on the relay!


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