Hi! Normally, after switching the engine off, the ECU fan would come on when it's hot, runs for a few minutes, then shutoff. However, lately, it's been coming on but not shutting off even after 20 minutes. The ECU and TCU modules inside are warm, but not hot to the touch. So what i'd do is turn the ignition key to position II, then turn off again; that process would shut down the ECU fan.

1. I'm assuming there's a sensor somewhere that controls the on/off power; what is it and where?
1. Does the ECU fan have it's own relay, or what relay does it use, if any?
2. if it's the ECU fan, does it have anything internal that could cause the power to not cut-off?
2. Any other thoughts?

Need some help pls. Thanks.

 

Are you sure it isn't the after blow feature that is designed to dry out the A/C evap? If you haven't ever had a Volvo it can be a bit unsettling if you aren't expecting it, but the HVAC fan can run intermittently for an hour or so after you park to prevent mold/mildew occurring. There is a battery voltage sensor in the mix so that it doesn't run if it will run the battery too low for the next start.

 

Thanks pkrface for your reply.

I know what you're talking about coz whenever i've used the A/C, i've heard the HVAC fan kick in after about 50 minutes after engine shutoff.

The ECU fan kicks in seconds after engine shutoff, but should run only for a few minutes. Mine won't shutoff.

Just wondering if the sensor is internal in the ECU fan so it switches itself on or off, or the ECU uses another sensor and sends the signal to the fan to shut on or off.