radiator fans not coming on with temperature, only a/c
 

mods please don't move this to maintenance/repairs. I'll get more informative answers here since it is pertaining to FI

Well I had some overheating issues when driving hard, and noticed the heat was up at a stand still. I put in a mishimoto which cured the driving hard heat.. but still heated up at a stop. So of course i immediately assume fans. Turn a/c on to cut on a/c fan and the temp dropped immediately. I assumed 1 fan was for ac and one for temp. Turned a/c on and both fans come on, so it's not a bad fan as i assumed.

PROBLEM: Fan will not cut on with temp. (200+ degrees and no fan)

CHANGES: Only notable change since issue is Haltech. This doesn't control fans in any way, does it?

Any ideas would be appreciated. There is a recall for the fans, but i think it's for the fan assembly itself, not wiring/controls

ross

No Haltech doesn't control the stock fans. There are three relays used in the stock fan set up as I recall: hi speed, lo speed, and the ground relay. Each fan has a double winding so both fans operate at LOW speed if only low relay on or HIGH speed if low+high relays triggered. I believe the AC has a separate trigger and it triggers either or both relays depending on the pressure in the condenser.

With the AC off if neither fan kicks in, then I would guess it's the coolant temp sensor. This is easy to test because you can see the coolant temp in the Haltech ECU manager (set up a gauge and tune display that channel).

The alternative is that the one of the relays or fuses feeding the relays is shot but if this is the case, you should still get low speed on the fans (I think). If both relays or fuses were out, then you wouldn't get fans with the AC.

The other thing to note is that different model years have slightly different wiring of the fans (in the IPDM behind the battery). Best to check your FSM for your specific model/year. You can also use Cipher to troubleshoot if you have it, but I think ECU mgr is easier.

thanks, i'll check the relays today. the cts in fine.

ross

When I wanted to wire up my aftermarket fan controller using the stock triggers, I made some notes, attached (for my 2004 G35 coupe). I would recommend finding the same pages for your model/year.