here is a diagram showing the link between ecu and fans . ECUports ACS85 grounds the A/C relay and FANH A12 grounds both the A/C relay directly and the cooling fan (radiator switch on the diagram) indirectly through the Timer. So I think that the dblue wire from the timer (or to the timer) that i cut is linked to port ACS85 and when I cut it broke the ground to th A/C relay and that fan shut down. So armed with this new info I believe that it is either the ECU at fault or even possibly the heater A/C control in dash that is signaling the ECU......holy smokes, is this ever a complicated way to run a fan.......
blue wire is connected to fan A12

 

Just me but PA asked about the AC Pressure switch, please verify that.

With the AC off and blower off, key on.....are you getting ground from the ECU. On your pin out I'll call it a12, check a15 as well.

 

halcyon, I have the same problem as you.. Both fans run full time with the key energized.

I have not put much time into the problem, but this is what I have done so far..
- disconnected both fan control temp sensors (no change)
- Installed a flebay timer (no change)
- Installed an HVAC head from a buddies accord; parting out! (no change)
- If I remove the corresponding Fuse/relay the fan will stop.
- If I remove the fuse #8 for the Heater control both fans stop.
- If I shut down on a hot summer day the fan timer "WILL" run the radiator fan for a short time.

I have thought about checking the ECM for a ground signal I just havent gone that far yet. I'm looking at the A12 trace on your schematic, not clear there is a connection for the Radiator fan relay Control "Coil" I don't see a black Dot at the ground "intersection" for the two ground wires. Yet the scenario of the ECM providing a ground command would make scense.. keep us posted

mike..

 

covered the question regarding the a/c switch in post #10 With "ALL" switches disconected including the ECU and fan timer and the in dash A/C control switch the fans still run. I must pull fuse or relay to shut down corresponding fan. I believe at this time that it is the "blue" or "blue/black wires in the diagram that are shorted somewhere, providing a ground for the relays. so instead of completely dismanteling my car, (although it is almost there now ) I thought i would just replace the blue wires to each component and try that. that is when i noticed the diode on the blue wire to the ECU, could it be that? and where is it? I checked the blue in to A12 with it everything still disconnected an it still has ground. As you can see in the diagram that the blue wire is spliced (one splice is two blue wires to one terminal on the condenser relay) 5 ways, the two relays , the timer, the ECU and the dash control A/C switch via a diode.

 

http://repairguide.autozone.com/znet...528005fa2d.gif
here is a clearer schematic with color codes. the diode is between the condensor fan relay and the A/C pressure switch.

 

I think that you are to the point where you need a volt meter and need to do some testing at the radiator fan and the condenser fan relays.

Unplug the relay and test for ground on that blue wire. Then unplug a suspect component, then test for ground again. Once you isolate the problem, then you can decide what needs to happen next.

I hope this makes sense.

 

well, at this point i have the ECU unplugged, the timer unpluged, both thermoswitches A and B unplugged, both of the A/C system relays unplugged the heater fan switch(in dash), and the cooling fan relay unplugged. Yet when I test the blue wire at the ECU pinout fan 12 and the coresponding pin out blu wire to timer and blue wires to A/C relay and test to chassis ground i get 0 hms where there should be no continuity at all there are 4 different blue wires and one blue /black all joined together by the variuos components in this system. and the one to the dash heater switch has a diode in the circuit.my head is a bit foggy with trying to find the red herring, could it be the diode ?

 

I wanted you to verify that you have tested using a volt meter.

The blu wire is connected at all those spots, so you can test at one spot for ground.

I would suggest to unplug the diode and test for ground on that blu wire. The diode is not in an easy to describe location. It is above the fuse box under the dash. I think it is either above or just at the top of the driver's kick panel. It will have a blu and a blu/blk wire going to it.

 

Thanks PA, will try to locate the diode this morning. I have done a thorough testing of all the components that I am able to using a multimeter, guess I wasn't clear on that , my appologies, that was long before my first post here.

 

halcyon, have you had any luck with locating the Diode?