A cooling fan conundrum

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#21

05-05-2013, 03:19 PM

halcyon

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Join Date: Apr 2013

Location: Vancouver, B.C.

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Quote:

Originally Posted by desertmike1

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

No , I never did find it,but I did solve the problem. after taking the dash apart, to trace wiring from fan timer to the ecu via the heater panel could find no visible issues with the harness. So to be sure I cut the bue wires (ground) at each component in the cabin and still the wires were going to ground. So next I went under the hood. Followed the same procedure to all components and still had the same results. At this point I decided to install a completely new, simple circuit to run the cooling fans using new relays etc and the existing switches which I already had tested and confirmed good. 30 minutes later I had it all wired up,tuned the key on and bamm on come the fans

. OK, I said to myself, the only thing old is the green plug to the thermo switch. so I cut the plug out, tested with the ohm meter and ......proceeded to dismantle #%@^& plug cleaned the dielectric crud out and discovered that someone (as in not me) most probably using a test light, had mangled the crimp portions of the pin and they where in contact with each other

. A poke with probe and a little dab of silicon and good as new, problerm solved. 2 hours of reassembling the interior ansd returning the underhood to stock and now back to the previous owners complaint of intermittant temperature spikes at idle . So now onto replacing the thermostat and, fingers crossed that will be an easy fix.

#22

05-06-2013, 10:52 AM

desertmike1

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Join Date: Apr 2011

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Well this is good news, you hung in there.. I give you alot of credit for that one.. Now I need to get Serious about mine. Thanks for checking in..

#23

05-06-2013, 01:15 PM

halcyon

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Join Date: Apr 2013

Location: Vancouver, B.C.

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Quote:

Originally Posted by desertmike1

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..

Yes although it does not show it in that diagram both relays are grounded by the ecu. the diodes are there to prevent the larger cooling fan from turning on when the timer turns on the smaller A/C fan. The ecu is the "co-ordinator between the demands of the A/C system and the cooling system. I would check the back side of each plug first as there is very little to prevent the two wires from touching if someone has stuck a probe in there, they are only a 1/8 of an inch apart.