Scratching my head on this.....updated all the A/C o rings to convert system over. Only thing I have changed. Now the fan will continue to run after turning the car off and will not kick off. I tested the run on fan and it doesn't kick in when grounded (should according to bentley). If I start the car and it is cold, turn the A/C selector and the blower switch to one, the fan kicks in and will not turn off. I pulled the A/C relay and it still does the same thing. Pulled the run on relay and same thing. If I pull the connector for the thermo switch on the radiator the fan continues to run. lol. If I pull the battery cable it resets it self.
Note: If turning the key switch on and the selector to a/c or defrost and the blower switch to one the fan kicks in even without starting the car. Have to pull batt cable to reset.
bump.....changed the a/c relay and the fan relay on the fender and still no change.
fan still runs when the sensor unplugged on the radiator and still runs when pulling the wire from the run on sensor. Also turn the key on when cold, place lever in a/c mode and turn the blower on and high fan kicks on immediately (as it should) but just will not go back off until pulling battery cable.
Theres a temperature sensor usually bolted to a metal plate, bolted to the valve cover...drivers rear side of the engine. It makes the fan kick on when the under hood temps get too hot. it has a single wire going to it.
see if you can find that..and make sure that wire isn't grounded accidently.
While that switch can go bad, with the Key on can cause the Fan to run. it may also be located on the rear of the valve cover second nut to the right on the drivers side.
For a fan to stay on, for an indefinite time after the key off, id a puzzlement.
You have to look at the Bentley.
The Problem with this is that the Fan is in two different sections.
The first at current path 43-48 in the 91 section, that describes the basic function but leaves out a wide variety of sources.
Then in the a/c section where er see it in further light sans the after run area.
Getting it down to brass, there are 2 switches, one control unit, and one relay oh, and the motor itself.
The highest culprit is the relay that is located on the Drivers side of the battery tray in front of the battery mounted to the fender.,,,
This relay is part of the after-fan run, and the a/c fan run. It is the only relay that is directly tied to the 12v battery source of the fan if you have a/c. If that relay goes bad as in shorted the contacts then 12v is applied to the fan all the time. If the relay goes open, then the fan can never run.
If I was you, I would look for corrosion on the relay housing for the fan at the bottom of the relay
on the drivers side of the battery. Those relays are subject to spray from the road and I have had them go open and closed, from rust for a better adjective. This rust is Iron and as we know Iron is a conductor.
Your symptoms are a little strange as removing that relay the fan stays on, leads me to believe that some one may have used creative wiring techniques, that you will have to discover.
So start at the basics, as in Checking all the Fuses with a meter, as grounds and voltage can back feed a circuit.
Then you didn't say if the fan was in "high" speed or "low" speed which would then get you on to one of the two sides of the motor.
Since the Motor is also fed a ground as it is insulated from the chassis, I would also ask, have you replaced your battery to frame and frame to engine/tranny grounds yet? If not let me say that many a flaky electronic issue is resolved by flaky ground removal.
Since resetting the ground or power to the car causes a reset, then you are having a relay that is sticking and controled by the fan switch, so you can't discount the a/c relay as a issue either.
So that is the after fan run relay.
The a/c relay
The fan motor relay near the battery.
To discount the fan run on switch which is on the valve cover you can disconnect it and tape it off
to isolate it as an issue. Then if that is stopping the fan, then you have found that it is the after fan run relay, and the battery relay or creative wiring between the two.
Now with that said, your after fan run can run for up to 15 minutes after the key switch is shut off, and the key removed from the car...which os directly controlled by the after fan run relay labeled 31 in the fuse panel, where the a/c is 13 usually....
Grounds, Grounds, Grounds Replace them things.
Divorces, Great Coffee, and Electrics, all start with GOOD Grounds. Where are my grounds ?
thanks Briano!!!! you always give great explanations. I think I finally have it narrowed down to the actual fan motor.....Replaced the relay next to the battery last night just to be sure, no change. Took my meter this afternoon and checked power to the fan....with the key on and a/c switch/blower on, the connector showed power to the fan in high as it should. After turning off the key, blower and swapping the lever from a/c, the connector still had power on it to the fan. I unhooked the connector and checked for power and it no longer had power. So....I left it unhooked and verified the power was getting to the connector and turning off as it should which it was every time. But, when hooking it back to the fan and repeating, power seemed to be stuck in the connector when everything turned off until the connector was removed. Reinstall the connector and all good.
Something in the motor seems to be sticking after the fan kicks in and not cycling off and is holding power to the connector? Strange but the fact power to the connector works as it should when unhooked tells me it is functioning correct. There are no other wires connected to the motor so seems it has to be in the motor at this point.