garretthes

On my 59 Suburban with 2004 5.3 we used a single electric cooling fan. We wired it with 10 gauge wire to a 40 amp relay. After two years the relay melted at connectors 30 and 87. The wire connected to these terminals was also charred. Do I need a different relay? Puzzled

RPM WS6

iTrader: (3)

Hmmm.... 10 gauge wire and 40 amps should be plenty. What is the amp rating for the fan motor? I'm using a single fan on my Nova; 14 gauge wire, no relay, and a 20 amp fuse. It's been fine since forever, but it's only a 10 amp fan motor.

Pocket

iTrader: (22)

Could have simply been a bad relay

Old Kid

Any idea what the fan is out of and what it originally had for a relay? Your 40 amp relay may have been at it's limits. The fan could be failing causing a higher than normal draw. The most likely suspect is the connections at the relay becoming loose or dirty. Lots of heat at bad connections. Just like welding!

Pop N Wood

iTrader: (1)

I agree with old kid that is probably just a bad connection. The current draw through an electric motor goes way up if it run with a low voltage. As the connections get worse, the voltage drop gets worse and the fan draws even more current. Maybe you just got a bad initial crimp or something.

The relay melted due to excessive current draw, but there are all kinds of things that could have caused the current draw. Like bad brushes in the fan or insufficient wiring somewhere else.

I would replace the relay and connectors with similar stuff cause it is cheap. I like to solder crimps for added insurance. Then measure the volts at the fan when it is running. See if you can measure the current draw too. That will remove the known bad connectors and should tell you if the wiring set up is sufficient for the fan you have.

usmcz28

iTrader: (3)

I know a lot of people are mocking up Taurus/MarkVIII fans into older cars. They flow over 4000 CFM and a company call Hollister Road company sells relay kits for fabbing in the fans. They can also use temp probes to turn the fans from low to high depending on temp and AC use. I picked one up for my LSx swap in my 1980 Z28 and i'll be using a Taurus fan.




http://www.hollisterroad.com/proddet...?prod=MarkVIII

garretthes

Thanks for the help guys. It appears the crimps where good. I seriously doubt it was a bad connection. The fan was purchased at Advanced Auto and I can't remember the voltage draw. I'm guessing it was a bad relay. My brother used 4 of these relays together when he wired the truck. The heater fan relay died within 6 months. That could be a clue.
I replaced the relay with a different 40amp and of course removed all the bad wire. Hopefully it will be OK. I will check it periodically for signs of heat.
I can't have this happen while my wife is driving!

MN-Brent

Get the Bosch or Tyco 75 amp relay. Its what I run for the Mark VIII fan. Overkill with this component is money well spent. Dont want to be stranded or end up with engine damage. They operate the same as your 30-40A Bosch style relays. I had to order it online as no auto parts store carried it. I got 2 so I have a spare, just in case.

http://www.amazon.com/TYCO-BR-5000-7.../dp/B001PT9X9E

Also I recommend an inline fuse upgrade. Im using a 60Amp inline maxi fuse to go with it.