2 Fan temp settings
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On The Tree
Joined: Dec 2014
Posts: 147
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From: Mid Missouri
2 Fan temp settings Currently looking at a 2 fan set up for my swap, 64 Chevelle 6.0L/ 4L65E/ Vintage Air. I'm leaving everything stock (no power adders) but about to have the ECU flashed and am wondering if I need to have a different temp setting for fan 2 for the ac? No radiator yet. What should I look at with this in mind?
You need some provision for kicking a/the fan/fans on whenever the a/c needs heat pulled from the condenser INDEPENDENT of temp control for the engine. If your ecu doesn’t have a “soft start” feature, I’d use two different fan temp settings for engine cooling just so both fans aren’t “hitting” the electrical system at the same time on start-up and shut down. Be sure you keep the temps far enough above whatever operating temp your t’stat is trying to control to so the fan(s) aren’t running all the time once up to op temp.
Ha! First suggestion = no assumptions. And, you won’t assume an operating temp. You’ll DETERMINE the op temp based on your t’stat and fan temp settings. What temp t’stat? My experience has been add 6 - 10F to t’stat temp to obtain operating temp for coolant leaving the block (@ ecu temp sensor in driver’s side head).
My 187F t’stat (oem in LS3 crate) results in operating temps in the 195-197F range when t’stat is controlling - under cruise with plenty of air moving across rad/fans off. Given that, I set my PWM variable speed controller at 202F - a good 5F above operating temp. And magically, mine sits right at 202-205F when fans are contolling. If ecu is triggering 2 relays, to manage a 195F operating temp I’d have first fan on at 212F/off at 202F. Second fan on at 220F/off at 210F.
Obviously, if your t'stat temp is different -- you need to do some addition/subtraction math....
My 187F t’stat (oem in LS3 crate) results in operating temps in the 195-197F range when t’stat is controlling - under cruise with plenty of air moving across rad/fans off. Given that, I set my PWM variable speed controller at 202F - a good 5F above operating temp. And magically, mine sits right at 202-205F when fans are contolling. If ecu is triggering 2 relays, to manage a 195F operating temp I’d have first fan on at 212F/off at 202F. Second fan on at 220F/off at 210F.
Obviously, if your t'stat temp is different -- you need to do some addition/subtraction math....
Last edited by Michael Yount; Jul 21, 2019 at 07:45 PM.
