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I have been slowly piecing together an electric cooling fan setup and have a question regarding relay and fuse sizing. The fan I bought is a two fan setup that I will trigger with the FiTech system. For simplicity I will run both fans at once. The fans have an advertised draw, for both fans, of 30 amps. Would it be appropriate to use a 40 amp relay and 40 amp fuse in this scenario? Something like this ( https://www.summitracing.com/parts/spu-ix-frh )? If not, what would be appropriate, or what additional information would I need to make that determination? As always, I appreciate any feedback the forum can provide.
Both fans 30amps? That doesn't seem right. When it comes to fans and cooling I would run each on their own for several reasons. Total draw and power, stagging the fans you really don't need both all the time, and safety. If you melt it cause you over draw or blow the fuse or relay you are DOA and now stuck.
Both fans 30amps? That doesn't seem right. When it comes to fans and cooling I would run each on their own for several reasons. Total draw and power, stagging the fans you really don't need both all the time, and safety. If you melt it cause you over draw or blow the fuse or relay you are DOA and now stuck.
Fair point and thank you for your input. I have considered running one fan off of the Fitech, come on at say 185, and then have the other fan connected to a seperate temp sender, coming on at say 195. Each on its own 30 amp relay. I very well may go with that approach. For my own edification though, I still wonder about the original question. Assuming the 30 amp draw for both fans is correct, would a 40 amp relay be sufficient?
Yes, that would work. I run the Holley hp on my car I have 3 relays and a 160 stat. The first fan kicks in at 195 turns off at 185, second at 205 turns off at 185 with the first fan. Third relay is for the AC to kick the first fan on when it needs to. Don't forget the diode you don't want to feed a ground back into your system. Sorry I'm also using 04 GTO fans so needed 3 for full speed and again I don't want any feedback into my ECU.
Yes, that would work. I run the Holley hp on my car I have 3 relays and a 160 stat. The first fan kicks in at 195 turns off at 185, second at 205 turns off at 185 with the first fan. Third relay is for the AC to kick the first fan on when it needs to. Don't forget the diode you don't want to feed a ground back into your system. Sorry I'm also using 04 GTO fans so needed 3 for full speed and again I don't want any feedback into my ECU.
All good info. Thanks for that. Do you put one diode for each relay and where do they go? Between the signal (ECU, Temp sender) and the relay?
In my case I only put one on the AC relay that shares ground. You would put it in line at the ground wire right at the relay. If your wiring is clean and you have your ecu sending the ground to turn on the fans then its not needed. If you going to add anything else to that wire then you should even a manual override switch I would.
In my case I only put one on the AC relay that shares ground. You would put it in line at the ground wire right at the relay. If your wiring is clean and you have your ecu sending the ground to turn on the fans then its not needed. If you going to add anything else to that wire then you should even a manual override switch I would.
Ok, that makes sense. Thanks a lot for taking the time to explain. Very much appreciated.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
i would invest in a fan controller instead of a thermostat switch. They ramp up slowly, can contol 2 fans seperately (if you buy that type) and are adjustable for on temp. I just installed a Derale PWM controller. The Derale wants a seperate power and ground from the battery to prevent feedback and crosstalk.
I have a single fan that i ran for 2 years and last summer the plug connection must have gotten contaminated. It melted and i had to hard wire it while on the road. It also was 0 to 100% everytime it came on which probably want helping
Last edited by Rescue Rogers; May 2, 2020 at 07:39 AM.
i would invest in a fan controller instead of a thermostat switch. They ramp up slowly, can contol 2 fans seperately (if you buy that type) and are adjustable for on temp. I just installed a Derale PWM controller. The Derale wants a seperate power and ground from the battery to prevent feedback and crosstalk.
I have a single fan that i ran for 2 years and last summer the plug connection must have gotten contaminated. It melted and i had to hard wire it while on the road. It also was 0 to 100% everytime it came on which probably want helping
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
mine mounted on the fender using rubber well nuts
I just got it running today after a new roller cam and cooling system and 5 speed. Stayed at 205* in the garage with no air flow and idling away while I tried to set the timing and get stable idle. The motor needs adjustment but at higher RPM it purrs right along.....no oil leaks, just one cooling hose that was loose and a bad hydraulic clutch line that was leaking at the factory crimp....I cant find who I bought it from but it is complete gargbage. I have a new McLeod comng this week from Summit. I wish I had stock in them, UPS, Jegs, Ebay, Amazon and Fedex. They are all making money
Last edited by Rescue Rogers; May 2, 2020 at 04:03 PM.
i would invest in a fan controller instead of a thermostat switch. They ramp up slowly, can contol 2 fans seperately (if you buy that type) and are adjustable for on temp. I just installed a Derale PWM controller. The Derale wants a seperate power and ground from the battery to prevent feedback and crosstalk.
I have a single fan that i ran for 2 years and last summer the plug connection must have gotten contaminated. It melted and i had to hard wire it while on the road. It also was 0 to 100% everytime it came on which probably want helping
Interesting idea. Definitely worth considering. Thanks for that. I was reading the install instructions and have a question for you. They state that the controller must be within 5 feet of the battery and shouldn't be mounted near engine heat. Did you connect to the battery and have you seen any issues with your mounting location?
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
So far no isues, I just got he car fired up to day and it kicked on fine. I ran both the power and ground back to the battery and added in a relay at the firewall inside the passenger compartment so when the battery disconnect is off the power is shut off. I also added the remote on/off as well
Last edited by Rescue Rogers; May 2, 2020 at 05:38 PM.
Electric cooling fan question
