1999 Honda Cr-v
Built Turbo b20
Hondata s300 on p28 with Zerg industries jumper harness

Here's the deal:

My p28 will not turn the fans on when the A/C is turned on... Only once the temp switch tells the fans to turn on.

I put the stock ecu in, fans turn on when A/C is turned on...

I have checked the jumper harness and the FANC wire converts properly.

Does anyone have any input on the topic?

 

Try the ECU in a vehicle you know the fan control is working in and see if this ECU works. You can also try a known workign ECU in this vehicle and see if it still works. This will help you determin if is a faulty ECU or a problem with the way this vehicle is wired. This will not be an issue with the the s300 if everything else is working.

 

Parameters - Protection - Radiator Fan
just override it. if it still doesn't work, the ECU is probably bad or the S300 not installed properly. Or you may have a bad rom, try starting with a different base