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Author Topic: Fan relay wires getting hot: FD Ls1  (Read 1254 times)

Offline mslam02

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Fan relay wires getting hot: FD Ls1
« on: May 25, 2010, 12:33:45 PM »
I have the dual hinson fan setup, and have been running this for about 7k miles... Now, what i believe to be all of a sudden (could have been happening for a while, but unsure) The fan relay is getting insanely hot and destroyed the relay. No changes to the car's electrical have been made since the build... The fuse from the battery to the relay has not blown (30amp) but it looks like, (i haven't check yet)  the power wire to fans, and maybe the ground wires getting hot...

Some one mentioned the motors on the fans could be going bad, is that possible with them only being used for 7k miles?

I have an eat pez harness and have contacted him about the issue, but as most of you know, it can be difficult to get a hold of him, especially now that v8rx7forum is down.

Any help would be great, as i am not the greatest with wiring gremlins...
Thank you.

Offline danzan

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Re: Fan relay wires getting hot: FD Ls1
« Reply #1 on: May 25, 2010, 01:11:21 PM »
I have the dual hinson fan setup, and have been running this for about 7k miles... The fan relay is getting insanely hot and destroyed the relay. The fuse from the battery to the relay has not blown (30amp)

Some one mentioned the motors on the fans could be going bad, is that possible with them only being used for 7k miles?

you are not drawing too much current, or the fuse would blow.  so your fan motors should be fine.

sounds like your relay is undersized, or the internal relay contacts are bad, & have high resistance.

if you have 2 fans, & they go on simultaneously,  make sure that your relay is rated for at least 60 amps, or that you wire 2, 30 amp relays in parallel.

if you have properly sized relays, then check the relay resistance.

to check that, measure the voltage drop across the fan relay contacts, while the fans are on.  there should be close to zero voltage dropped across the relay contacts, between the battery side & the fan side.

« Last Edit: May 25, 2010, 01:13:58 PM by danzan »
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Offline mslam02

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Re: Fan relay wires getting hot: FD Ls1
« Reply #2 on: May 25, 2010, 01:24:18 PM »
ok, i wish i had the car with me, its either a 50 amp or 30 amp relay in there right now... I will switch this out, and see what happens

Thank you.

Offline NoClassic

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Re: Fan relay wires getting hot: FD Ls1
« Reply #3 on: May 25, 2010, 01:42:50 PM »
Check your grounds.


Offline danzan

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Re: Fan relay wires getting hot: FD Ls1
« Reply #4 on: May 25, 2010, 02:20:36 PM »
Check your grounds.

that's a nice general answer, & it never hurts, but i do not see how his reported symptom has anything to do with grounding.

what am i missing?  serious question
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Offline NoClassic

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Re: Fan relay wires getting hot: FD Ls1
« Reply #5 on: May 25, 2010, 03:05:58 PM »
A hot relay has to mean there is excess resistance somewhere, correct?

Unless he just has cheap relays that has to mean a bad connection.

Generally I have found that people spend plenty of time on the power side but overlook the importance of their grounds and just throw it on any old bolt within the bay. Maybe they sand off some paint. Without anything to prevent oxidation on bare metal it will occur quickly depending upon climate.

I suppose he should really check the entire system for corrosion or bad solder/crimp joints. I just think the grounds are the most likely place for this to occur.

Offline danzan

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Re: Fan relay wires getting hot: FD Ls1
« Reply #6 on: May 25, 2010, 03:17:50 PM »
A hot relay has to mean there is excess resistance somewhere, correct?

yes, within the relay itself.  if there were excess resistance, external to the relay, then there would be LESS current flowing thru the relay. 

voltage drops are across the resistance.  no resistance=no voltage drop.

E=IR  Ohm's law.  Should be Dan's law

i remember, when i was having a beer with Mr Georg Simon Ohm, Mr Andre-Marie Ampere & Mr Alesandro Volta in ~1832.
Alle was rubbing a glass rod with cats fur & shocking us.  i had to explain what was happening.

As is often the case, they got all the fame & credit.   i am still just guzzling beer. ;)
« Last Edit: May 25, 2010, 04:47:55 PM by danzan »
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Offline NoClassic

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Re: Fan relay wires getting hot: FD Ls1
« Reply #7 on: May 25, 2010, 03:35:45 PM »
What do you feel is the likely cause of the problem?

It sounds like he has replaced the relay already.

Should that not have corrected the issue?

Offline danzan

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Re: Fan relay wires getting hot: FD Ls1
« Reply #8 on: May 25, 2010, 03:40:19 PM »
What do you feel is the likely cause of the problem?

It sounds like he has replaced the relay already.

Should that not have corrected the issue?

could be an undersized relay.  especially, if he has 2 fans that turn on together.  that could draw 50-60 total amps & fry the relay contacts.
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Re: Fan relay wires getting hot: FD Ls1
« Reply #9 on: May 25, 2010, 03:42:03 PM »
What relay does pez use in his harness and what fans come with the hinsons kit?

Offline danzan

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Re: Fan relay wires getting hot: FD Ls1
« Reply #10 on: May 25, 2010, 03:51:22 PM »
What relay does pez use in his harness and what fans come with the hinsons kit?

depends on how the fans are controlled.  if both PCM fan controls (high temp & low temp,) , are used, then the fans would be operated independently & 2 relays would be used.  it depends what the customer told Pez.

earlier hinson cooling systems came with one fan.  IMBWB, i think that the later versions have two fans, which allows them to be controlled independently.

i may have missed it, but the OP, has not told us about his setup.
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Offline mslam02

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Re: Fan relay wires getting hot: FD Ls1
« Reply #11 on: May 25, 2010, 03:56:05 PM »
They are SPAL fans, heres the link to the kit
http://www.hinsonsupercars.com/p-751-1993-99-rx7-lsx-v8-premium-cooling-system.aspx

Greg (eat pez) had me order the relays i believe. Maybe he wasn't aware i was running the dual fans, though i was sure i told him... this was over a year ago, can't remember exactly.

This is the info on the relay i just grabbed that went bad.

SONG CHUAN
896H-1CH-D
Coil:12VDC
50A/30A
14VDC

only 4 wires come off the 5 prong relay (center is not used) so im assuming i was running 30 amps

My setup is configured so the ecu turns on both fans at once for the low temp, utilizing one relay

Offline danzan

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Re: Fan relay wires getting hot: FD Ls1
« Reply #12 on: May 25, 2010, 04:04:38 PM »
They are SPAL fans, heres the link to the kit

My setup is configured so the ecu turns on both fans at once for the low temp, utilizing one relay

why are you turning both fans on at once, when the PCM makes it easy to sequence them?

however, being that as it may, you need a 60 amp relay if you are turning them on at once.  or, you can use a 30 amp relay in each fan's power wire.

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Offline mslam02

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Re: Fan relay wires getting hot: FD Ls1
« Reply #13 on: May 25, 2010, 04:11:56 PM »
They are SPAL fans, heres the link to the kit

My setup is configured so the ecu turns on both fans at once for the low temp, utilizing one relay

why are you turning both fans on at once, when the PCM makes it easy to sequence them?

however, being that as it may, you need a 60 amp relay if you are turning them on at once.  or, you can use a 30 amp relay in each fan's power wire.

To keep temps down. What are the benefits to running them sequentially?

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Re: Fan relay wires getting hot: FD Ls1
« Reply #14 on: May 25, 2010, 04:16:36 PM »
To keep temps down. What are the benefits to running them sequentially?

you might not have fried your relay.

also, less cycling of the fan motors, which will result in longer life, because it is the starting surge that stresses electrical things
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