Electric Fan Relay Help

[RangerJoe]

At the end of last summer I did a Focus dual fan swap into my 93 gt. I used a cheap autozone dual fan thermostat kit. Ran the fan for very short time last summer before car went up for engine rebuild. This spring, start driving car and was blowing 30 amp fuses. Checked all wiring, no shorts and resistance was good. Eventually put a 40amp fuse in and had no problems. Been driving for a month like this.

Today, 80+ degrees and 45 minute drive. Started smelling burning plastic, fan stayed on when I pulled into garage and turned car off. Tapped on relay, fan turned off. Pulled relay, melting around #30 pin, which carries the main power from a 10gauge wire.

I know these fans pull alot of amps, apparently 30+ amps. The relay has the markings "12VDC 40/30A". I assume this relay is supposed to be good for 30 or 40 amps. Is this right? I don't believe the 10 guage wires are being overpowered, and the 40 amp fuse is not blowing. Do I need to upgrade to a true 40amp fuse? I know there are really nice controllers out there that are highly recommended, but the cost is an issue at the moment. Maybe not at the end of the summmer, but right now it is.

Can I put a 40amp relay in and drive, or do you think there is another problem here? I would think the 10gauge wire would melt or get really hot, or the fuse would blow if they were the weak link. I am thinking that the relay is the weak link here. Any ideas?

Thanks!

 

[jrichker]

The push on tab connectors used to connect the relay to the wiring do not always make good contact. That is why they get hot and overheat or sometimes even fail. The more the heat up, the more resistance they create, the more heat that creates. Clean the relay tabs with a green Scotch-Brite pad and replace the push on wiring connectors or relay socket.

 

[RangerJoe]

I will give this a try and see how it goes. Thanks.

 

[Stever89]

In my experience and reading, e-fans pull quite a bit, even more than 40A in many cases. I'm also wondering if what you smelled in the car was something other than that relay at #30. Take a look at your grounds. I just find it hard to believe that little #30 pin burnt enough for you to detect it in the car while driving.

I also have a fan controller I bought at O'reilly, a Hastings relay. I had the same troubles you were, so I put another relay between the high speed output and the fan.

http://www.aecsensors.com/DG85.pdf

 

[4rdnut]

amp pigs

I don't know why people want these high amp drawing "oem" electric fans when the aftermarket electric fans draw half the amps and come with the correct wiring and fuses. I think the oem fans have a 60 plus amp surge when they kick on. You also have to invest in the right controller. The cheap controllers turn the fans on all at once giving that high amp surge, you want one that gradually spin the fans on. It's easy to buy a contour fan or mark iv fan etc. on ebay without getting the oem wiring and relays and correct wiring diagram and controller that should come with it.

 

[RangerJoe]

Thanks for the link. I brought the relay inside and set it on the desk while I typed this post. My wife was in the room about 30 seconds when she asked me what the smell was. Even though the relay has cooled, it stills smells like burnt plastic. I will check my grounds though just to make sure.

4rdnut; I did the swap as a cheap (yes, cheap) upgrade last summer. I am going to make one more attempt to straighten this out, if it doesn't work out, then I will probably save my coin and buy an aftermarket kit that is already put together.

Thanks for the help guys, any other advice is appreciated!

 

[BYRDPE]

go ahead and spens the $99 for a quality fan controller from summit. i too started with the $29 version...bout the varible speed version and couldn't be more pleased.
Flex-a-lite 33054 - Flex-a-lite Variable Speed Controllers - Overview - SummitRacing.com