Heater blower will not shut off after ignition is turned off an key is pulled.Purpule wire to motor has power going to it with dash controls out of dash. This is a 2oo2 olds Aurora with 92kmiles.I put new brushes in blower motor an when I plugged in harness blower motor started running half speed with on ignition off! So I pulled relay box next blower motor an has one wire with power going to it,thats puts power to purpule wire to blower.

Check for a dark blue wire , this is power to the blower motor .

bad news. that.
if the key is off, i check that IGN1 and IG2 and Accessory
pins on the key switch to be SURE they are at 0volts

if not i pull the Ignition switch connector, 0v now is bad switch.
12v is a major short in the cars electrical system.
shorting hot all time feed, to IGN1/2/Acc as it is.

the key switch kills all power to to the main fuse box. not marked
"hot all time" on the schematics.
free here
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

in this car , id look under dash and under hood for wiring hacks
I have this super accurate wiring Hack radar, can see it 25feet away.
the hands of the devil , are crystal clear.....

read this post on what's causing blower motor to run all the time.

http://ricksfreeautorepairadvice.com/blower-motor-wont-shut-off/
Blower motor wont shut off Ricks Free Auto Repair Advice

no back up lights mean back up reverse neutral switch is bad.use a 12 volt test light see if power going to blower motor or remove blower motor hot wire blower motor see if it works if not blower motor need replacing.if blower works when hot wired it.problem could be in ac and heater control switch faulty also resistor or check blower make sure it getting good ground.you could have poor ground at blower motor or electrical wiring going to blower motor could have a short or open.

I would venture to say that if you hit the dash and the motor started running then the problem would be in the heater control assembly mounted in the dash, like bad wire to Heater switch connection. A bad connection can jenerate a lot of heat and start melting things unless you find the problem soon enough. The switch may already be damaged inspect switches and wireing for any vissible damage and replace as required. However if everything looks ok with the heater control assembly, Their are a few more things you can check to be sure of before relpacing the heater blower motor. Turn the heater controles to the high heat and fan on high as well, settings and remove the heater blower motor pig tail and check to see if power is getting to the motor,( use a 12 volt test light at the wire harness side of this connection ) also check for power going to and leaving the blower motor resistor assembly ( mounted to the side or top of the blower motor housing ). If so equipped. If you find no power getting to the motor at this point then you will half to start working your way back through the wireing towords the heater controles until you find the problem. Using your test light. Now if you did have power going to the motor then replace the motor. Good Luck From Ernie @ RedDeer, Alberta, Canada.

CHECK HEATER AND AC IGNITION 10 AMP FUSE UNDER HOOD JUNCTION BOX.IF ALL IS GOOD CHECK BLOWER MOTOR FUSE AND RELAY.IF ALL LOOKS GOOD. TURN ON CONTROL SWITCH TO CHECK TO SEE IF POWER GOING TO BLOWER MOTOR IF YES BLOWER MOTOR BAD.IF NO POWER GOING TO BLOWER MOTOR FUSE AND RELAY GOOD.YOU HAVE BROKE WIRE BETWEEN SWITCH AND BLOWER MOTOR OR CONTROL SWITCH FAULTY. TO GET TO BLOWER MOTOR ITS LOCATED UNDER THE DASH ON PASSENGER BEHIND GLOVE COMPARTMONT YOU DONT HAVE TO REMOVE GLOVE BOX ITS JUST BELOW IT FAR BACK.YOU NEED TURN OFF RADIO FIRST THEN DISCONNECT NEGATIVE BATTERY CABLE WAIT 20 MINUTES THIS DISABLE AIRBAGS AND THE BCM.REMOVE BLOWER MOTOR HOTWIRE IT TO SEE IF ITS WORKS. IF NO BLOWER MOTOR NO GOOD.IF BLOWER MOTOR GOOD THE AC AND HTR CONTROL SWITCH IS BAD DEALERSHIP FIX.

the blower module is shorted out.

Find the blower motor on the passenger side just above where the passengers feet would be. You may need to remove a panel (fairly easy). You will see a round metal housing about 4" in diameter. Turn on the ignition key and blower motor. Then tap the housing with a small hammer or a screwdriver. If the blower comes on.....replace the motor. If not, find the wires leading to that motor, undo the connector and check for power and ground in them.(You did check fuses first...right?)

I take a shoot here you can try this. try pulling the fuse or fuses that go to your heater blower and heater controls. If it stops check your heater blower it may be going bad, if you find nothing there, leave the blower unplugged and try turning your key on and see if you still hear it. If so I would think that the heater control is mess up and open and close the air blend door or you may have a wire shorted out under the dash some where.

I would check to see if there is a short on the fan controller switch and the motor. sounds like a crossed wire, especially if it's ignoring your speed selection and running when the key is out. could be near the fuse box under the dash. the cig lighter circuit is live all the time as well as a couple others, it maybe crossing with it. I would pull the fuse panels assem down and check for crosses and shorts.