ac fan wont shut off when ign switch is turned off. if you turn fan switch to off posistion and turn ign switch back on it will shut off . swapped relays around in fuse box under hood and still acts the same. if it sounds like another relay or controller what and where. the ac wasnt getting below 70" degrees and found that problem the heater valve. i clamped heater hose off and it went to 42' degrees. i'm stuck on where to look without ford serv manual

 

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subscribing...my AC will only work on max ac and fan at full throttle.

 

Senix, the issue you describe is possibly a combination of two issues, an open circuit in the blower motor resistor, and a problem with the climate control switch. The high speed blower relay provides ground to the blower motor through either the resistor (resting position, for lower fan speeds) or directly via the relay (switched). Ground for the resistor is via the air flow selector switch. The switch also provides the ground for the blower motor relay coil to enable the blower motor relay when anything other than "Off" is selected via the climate control switches. A blower that works only on high speed is characteristic of an open blower motor resistor.

Mike, about the only part of this circuit that could enable the blower motor to continue to run after the ignition is turned off would be the blower motor relay. I think you need to check the coil of the relay when the key is off to determine if the coil is getting both power and ground when the key is off. The positive coil voltage is via fuse 2 (7.5A mini fuse) in the Instrument Panel Fuse Panel. This fuse should only have power when the key is in the Run position. If you were to pull this fuse when the blower motor is running and the blower motor stopped, you know the problem is not a stuck relay but instead something not shutting off power to the fuse when the key is off. Caseys is probably on the right track at that point.

-Rod

 

Thanks a bunch, I'd rep ya but I have to spread the love first.

 

Mike,
I'm guessing your Explorer has EATC (Auto Temp Control). You'll probably find that the Blower Speed Controller has failed. It takes the place of the Blower Resistor on models with EATC.
This is a common failure mode on Lincolns and Crown Vics with EATC. It is usually caused by a bad connection at the power transistor on the controller. If you have soldering skills you might be able to fix the module. I've repaired a lot of them.

 

the exploder doesnt have auto temp control it has manual control i didn't check fuse to see if still hot with key off. its been a while since i fixed ford trucks and remember how they always had either burnt or lousy terminal connections. i gotta try and find problem over weekend but sometimes you cant find problem till it just quits or its something simple and stupid right in front of you looking you in the face