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'07 3SS 2WD
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Discussion Starter · #1 ·
Here's why you don't run the HD Spal fan setup on the PCMofNC basic 3 relay system. It simply isn't built for the load. This failure almost took out my brand new 402 build.

You need to run the individual 3 relay truck kit. It's not listed for the TBSS, but it will fit. Hit up the fellas at PCMofNC for the correct harness.

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TrailblazerSS 3ss red
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in my opinion the 3 relay hd from racetronix is the best ive seen.its on my 07 3ss
 

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2008 TBSS Red Jewel RWD
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WOW that is crazy ... Glad it didn't catch on fire and burn it Burnit .... See what I did there

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Idk dude. Been running there spal fans and 3 relay kit for over 5 years with no issues.
 

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Lighter-than-you
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Relay controlled fans are becoming passe. Yes, they can be reliable and it helps when AWG fits the load but really PWM control is where its at. Lower electrical system voltage spikes, cooler and more consistent lower temps, less wiring, and best of all, no pcm control needed. Adjusting fan temp turn on is easy as turning a knob.
 
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Discussion Starter · #6 ·
Idk dude. Been running there spal fans and 3 relay kit for over 5 years with no issues.
The standard Spals or the HD ones? The basic kit isn't rated to run the HD units, IMO. It only has 1 12ga power and ground wires. The Truck kit has two each.

The HD fans can draw 40 amps each.
 

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The standard Spals or the HD ones? The basic kit isn't rated to run the HD units, IMO. It only has 1 12ga power and ground wires. The Truck kit has two each.

The HD fans can draw 40 amps each.
I guess I have standard spal since they didn’t come out with the hd spal fans until 2019. Had to go look on there site. Not sure why they even needed to upgrade the spal fans to hd since the standard spal fans work amazing. Looks like an up sell that causes problems like yours. Never had any issues with standard spals. HD spals are not necessary.
 
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Discussion Starter · #8 ·
I guess I have standard spal since they didn’t come out with the hd spal fans until 2019. Had to go look on there site. Not sure why they even needed to upgrade the spal fans to hd since the standard spal fans work amazing. Looks like an up sell that causes problems like yours. Never had any issues with standard spals. HD spals are not necessary.
The HD may not be necessary for most, but they are for guys in really hot climates that have heavily mod'd engines (like me in Phoenix). Even with the HD fans and ColdCase radiator the temp needle will swing passed 210 on occasions.
 
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Lighter-than-you
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I guess I have standard spal since they didn’t come out with the hd spal fans until 2019. Had to go look on there site. Not sure why they even needed to upgrade the spal fans to hd since the standard spal fans work amazing. Looks like an up sell that causes problems like yours. Never had any issues with standard spals. HD spals are not necessary.
Yeah the HD spals are totally unnecessary for our set-up.. the weak link is the rad itself w/ best upgrade being a stockish-size 2-core crossflow all-aluminum rad. HD spals are meant for pulling through a 4-core rad, ac condenser and trans cooler. PWM control would net better cooling performance than going to HD spals.
 

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The HD may not be necessary for most, but they are for guys in really hot climates that have heavily mod'd engines (like me in Phoenix). Even with the HD fans and ColdCase radiator the temp needle will swing passed 210 on occasions.
I’m in SoCal and it gets pretty hot here in the summers (110 degrees or more some times). I have almost every mod done including a super charger. I still run the stock radiator and 3 relay spal fan kit and never see over 210 on the hottest days. I have a Scott’s cowl hood which I think helps with getting the hot air out of the engine compartment though. The stock hood traps all the hot air from the engine, making it run hotter.
 

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Discussion Starter · #11 ·
What seemed to put the heating over the edge was when the cam went in. The bore/stroke made it even worse.

Prior to that, it was just headers and a tune with cheap ebay Camaro fans on the original radiator. No issues.
 

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Municipal fleet mechanic here. Can’t even estimate how many connectors I’ve found like this. If the wire gage (and terminals) are rated for a given amperage….stuff like this occurs occasionally. People like to throw blame at connectors…..but if your cooling fan is rated to pull 40 amps…..is worn/failing, and is pulling 55 amps….you get a melted connector. If 3 out of 5 relays sold for this application….start melting, then yea, maybe there’s a design/QC issue.

im not involved with any of this, just throwing in my two cents
 

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I have a 402ci stroker that seems way more susceptible to heating up, and use the PCMofNC with the 3 relay and manual switch HD Spals. I run the FSR radiator, 160 thermostat, condenser, intercooler. Agree that the aluminum radiators offer more cooling capacity, but had repeated relay failure.

Figuring out why, found the metal plate and the relay box was radiator temp. I got some Nylon 6/6 washers which resolved the heat soak, and no relay failures (knock on wood). The washers dropped temps 60+ degrees, From 200+ degrees to 140.

Best I can tell the all aluminum radiators (like FSR, Cold case) transfers the coolant temp, as factory plastic mount does not suffer from same heat soak (duh Physics, eh). Attached some snippets.

Agree with others - reach out to Kelly, as you have more options. She has been great to help.

factory radiator top is plastic.
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FSR has aluminum stand offs
 

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I have a 402ci stroker that seems way more susceptible to heating up, and use the PCMofNC with the 3 relay and manual switch HD Spals. I run the FSR radiator, 160 thermostat, condenser, intercooler. Agree that the aluminum radiators offer more cooling capacity, but had repeated relay failure.

Figuring out why, found the metal plate and the relay box was radiator temp. I got some Nylon 6/6 washers which resolved the heat soak, and no relay failures (knock on wood). The washers dropped temps 60+ degrees, From 200+ degrees to 140.

Best I can tell the all aluminum radiators (like FSR, Cold case) transfers the coolant temp, as factory plastic mount does not suffer from same heat soak (duh Physics, eh). Attached some snippets.

Agree with others - reach out to Kelly, as you have more options. She has been great to help.

factory radiator top is plastic.
View attachment 103272

FSR has aluminum stand offs
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Discussion Starter · #15 ·
Kelly was aware that the relay cover was warped when I was swapping from the Camaro fans to the HD. (Connector was fine at the time.) Didn't say sht about needing to run the truck kit.

When it failed, I emailed them again. Was basically told "sorry about your luck, buy the truck kit full price.".
 

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Kelly was aware that the relay cover was warped when I was swapping from the Camaro fans to the HD. (Connector was fine at the time.) Didn't say sht about needing to run the truck kit.

When it failed, I emailed them again. Was basically told "sorry about your luck, buy the truck kit full price.".
Are you running their 3 wire battery cable kit for TBSS?

Heat or current flow can potentially cause the higher current draw (to confirm you’re using non HD SPAL fans, correct?)

Too bad we’ve NOT got a time machine, to fan/harness amperage check (using an induction meter) to see which component is taking more amps.

I’m not using the truck harness with 3 separate relays, but we discussed as an option versus the 3 relay box system.
 

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Discussion Starter · #17 ·
Are you running their 3 wire battery cable kit for TBSS?

Heat or current flow can potentially cause the higher current draw (to confirm you’re using non HD SPAL fans, correct?)

Too bad we’ve NOT got a time machine, to fan/harness amperage check (using an induction meter) to see which component is taking more amps.

I’m not using the truck harness with 3 separate relays, but we discussed as an option versus the 3 relay box system.
No upgraded battery cable yet. Not that it would've made this situation a nonissue. I AM using the HD fans. The basic kit just isn't up to the task of the HD fans, and PCMof NC should make that point known.
 

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Just asking as a NOOB...would it have been better to run the fans with a "auto cool guy" controller?
This is my opinion, solely based on my experiences with car stereo and 12V systems.

The autocoolguy would have not experienced an issue if wired properly. 8ga to the battery, and 10ga to each fan.

The PCMofNC harnesses also wouldn't experience an issue if wired properly. 8ga battery hookups and 10ga fan leads. I highly doubt it's this size wire... It looks closer to a 10ga/12 setup or 12ga all around.

Things get worse when you're getting into aftermarket fans that can draw higher than 30A at peak current... Where I would ensure it's OFC wire, and solid hydraulically crimped ends.

IMO, the PCMofNC harnesses are built great for LS1 fans, or any other OE type fan. Current draw is low. But some of these aftermarket fans draw more than that, 50% more.
And $200 for wire and relays, and you still need hptuners for a tune. That's asinine. The aux controller is the same cost, without the tuning requirement. So cheaper, more flexible. It's almost a no-brainer. When the TBSS was new, in 2006, this was a great idea. It's 2021.
 

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Lighter-than-you
TrailblazerSS
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Just asking as a NOOB...would it have been better to run the fans with a "auto cool guy" controller?
PWM fan control is superior in every way to instant-on-low/high ecm/relay control.
 
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