so I jumped fan relay one and both fans turned on fine. the fuse is good. But when the car gets up to temperature the fans will not turn on by themselves. Ghosts or goblins?

 

Since it’s not listed, did you verify *all* of the relays are actually good - functioning properly though?

Otherwise the coolant sensor also has to be outputting the correct signal to the pcm for it to determine when to turn the fans on

please review this post and attached diagrams

https://www.rx8club.com/series-i-tro...4/#post4825732

not coming on at all initially would likely be relay #1 to check first, but possibly relay #3 failed over in the on position or is internally defective and not providing continuity in the normally-off position

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Okay so I have an aftermarket mishimoto fan shroud. I cleaned the connections and retaped them with electrical wire and seemingly had no effect. But then I drove around for a while and the fans came on after about 15 minutes in 85 degree weather which is still late. So I will be checking those items you listed next. Thanks for the quick reply man. I hope everybody is well with you and yours during this pandemic

 

Late relative to what exactly? Without actual coolant sensor temperature data you’re only guessing

Unless you changed the OE control system it will still operate the same as OE, but with two non-OE fans

Which again it’s entire function is based on all three relays and you haven’t addressed if they were all verified to be proper yet. It runs the fans at different mode combinations and speeds relative to coolant temperature, AC switch, etc. If one or more relays are bad it doesn’t mean they won’t run. It just won’t run in the mode being affected by that bad relay. Relay #1 is the most likely to impact the first fan operation mode likely to be needed, but again you can’t know what’s going on that way without knowing what the temperature set points are with the temperature sensor data.

It would more likely be a relay imo though. If you don’t have the skill set to check and verify them then get someone who does. Or take the cost is no object approach and replace all three. And even the coolant sensor too.

there’s also the possibility of one fan being bad that could impact the operation mode sequencing, but it seemed as though you verified both were working when you jumped around a relay, which again there are three total and you never stated which one that was.

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