Blown ac fan relays

[bottomline2000]

I've been having a problem with blown fan relays with my ac running.

Background-
Nelson wiring harness
New Dorman '13 escalade fans
Big 3 0 gauge wiring
DC power 270a alternator
Diehard platinum battery

I'm having a problem keeping the relay controlling the passenger fan on high with ac from overheating. All 3 relays are 30 amps and it seems like there is just too much power going thru the relay or resistance somewhere. Could a bad ground cause this problem because I am using the factory side mount ground from the battery and also the top mount ground to the engine as part of my big 3. If I remove the top mount ground and just rely on the factory ground the truck won't start like the battery is weak. Hook up the top mount big 3 ground and it starts fine.
Since I don't want to bandaid the problem by trying to run higher amperage relays if my problem is actually a grounding issue. . Any help would be much appreciated



sent from my lollipop

 

[bottomline2000]

Cleaned up factory ground. There was some corrosion inside the boot. Going to replace all relays with 40/60a relays and see how it does.

sent from my lollipop

 

[Rivieraracing]

Where does the Nelson harness put the relays at in relation to the motor? My old one I got from blackbear put it in front of the motor (due to lengths of wiring) and exposed them to alot more heat than needed to be, OEM puts it under the fuse box under the hood.

Also, how do the plugs that the relays plug into look? Any melting?

 

[bottomline2000]

The relays are mounted on the plastic cover that covers the pcm. I put a heat shield over them to keep direct heat off the relays. Only the area around one plug on the ac relay has melted plastic. The wire itself seems fine and the heat seems to have come from the relay since the base of the same relay pin has melted also.

I ran ac when the truck was cold so heat from the radiator wouldn't affect the relay and the ac relay started to heat up like the load was too high for it. I cleaned the connection up and slightly crimped the plug so the relay fit more snug. I would love to extend this harness to get the relays closer to the stock location.

@rivierracing where does the stock wiring harness get power? Does it connect at the junction box or directly to the battery? Just looking at power delivery and possible voltage drop.



The ac relay is on the right. These relays are rated at 30a but the guy at the parts store said they are not rating for cooling fans. Tells me this after i bought, installed and fried one...The 40a ones I ordered are.

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[bottomline2000]

Got the new relays a day early. Got em installed and everything works, ac is ice cold and temp control is kicking in like it should. The relays get warm but not scalding hot like before. Good thing is I got 6 relays for $20 so I have spares..hopefully I don't have to use them.

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[Rivieraracing]

I installed my OEM harness just like Scottyboy did, take a look when you get a moment!
http://www.tahoeyukonforum.com/threads/i-installed-e-fans-on-my-2001.28336/

 

[bottomline2000]

I installed my OEM harness just like Scottyboy did, take a look when you get a moment!
http://www.tahoeyukonforum.com/threads/i-installed-e-fans-on-my-2001.28336/

I'm all over that thread lol. Just as i suspected...I'm going to look into moving the power wires from the junction box to the battery.

Do you see any changes in your voltage when the fans activate..like a quick, big drop in voltage? With power coming off the battery I would hope not.

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[bottomline2000]

Well I changed out the connectors from my alternator to my junction box. Voltage shot up to around 14.8 which is the cold rating for the alt. It now stays above 14 when hot which I didn't do before. Must have been some resistance in the stupid connectors. Got some cheap copper ones from Home Depot and it's much better. Go figure.



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[Rivieraracing]

I'm all over that thread lol. Just as i suspected...I'm going to look into moving the power wires from the junction box to the battery.

Do you see any changes in your voltage when the fans activate..like a quick, big drop in voltage? With power coming off the battery I would hope not.

sent from my lollipop

Mine will fluctuate a bit, sometimes be at 14 and sometimes below that! I don't have the Big 3 done or a overdrive pulley for the alt.

 

[bottomline2000]

Mine will fluctuate a bit, sometimes be at 14 and sometimes below that! I don't have the Big 3 done or a overdrive pulley for the alt.

Mine sits pretty high now...finally feels like I'm getting full power out of this big alternator..


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