Blower fan runs high only on 2006 Ford Explorer

Could be one of blower motor relays contacts stuck closed . There are two blower motor relays 1 & 2 . One is located in the under hood fuse/relay box .
Or if your explore has automatic HVAC , it could be the front blower motor speed controller , this have been known to do this .
Which HVAC does your explorer have , manual or electronic automatic control.

Automatic or manual climate control ?

• The blower motor does not operate correctly - manual climate control

• Circuitry short
• A/C blower motor resistor
• A/C blower motor switch
• Blower motor high speed relay

• Go To Pinpoint Test O .

• The blower motor does not operate correctly - EATC

• Circuitry short/open
• A/C blower motor speed control
• EATC module

• Go To Pinpoint Test Q .

Pinpoint Test Q: The Blower Motor Does Not Operate Correctly - EATC
Normal Operation Under normal operation, the blower motor control module receives a 1-2 volt signal from the EATC module through circuit CH218 (GN/VT) to determine the desired blower motor speed. The EATC module receives a feedback voltage from the blower motor control module through circuit VH219 (GY) to determine actual blower motor speed. When the highest blower motor setting is selected, the EATC module sends 12 volts to the blower control module through circuit CH217 (BN).

Possible Causes
• An open, short to voltage, ground or together in circuits CH218 (GN/VT), VH219 (GY) or circuit CH217 (BN)
• Blower motor control module
• EATC module
• If automatic HVAC system i would suspect Blower motor control module .

Mike, 2006 Ford Explorer blower motor resistor location, under dash, passenger side bolted/screwed to plastic duct work/plenum right by the blower motor. Check the attached links,instruction and guides, Good luck
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http://www.autopartswarehouse.com/shop_years/ford-explorer-blower-motor-resistor-2006.html
2002 2005 Ford Explorer Blower Motor Only Works On High
2004 Expedition Blower Motor Resistor Install tutorial

Sounds like blower motor may be bad or even a fuse can be bad. Take a test light and check for voltage at blower motor, if none check at blower resister, but always check fuses first

heater blower motor resistor is defective....the resistor is not used when the fan switch is on high. Resistor requires replacement

You relay switch is stuck on. Replace it. Second thing to check is the fan switch may need to be replaced. If you turn off your engine and then back on does the heater fan go on even when it is turned off at the switch?

Remove the blower motor located under the hood on the passenger side in the evap. case. HEld in by 3 8mm screws. The fan blade may have broken .

sounds like the blower motor resistor assembly is bad.when it goes bad the fan defaults to high for safety purposes.

Look under the dash on passenger side and just to the left of the blower motor housing you will see the 4WD control module.Remove the 2 screws holding the module and let it hang down and your resistors are behind this.Remove the 2 screws holding the resistors and remove.
Now I am assuming you have manual climate control and not electonic.

if ur blower only came on the high fan speed i say it was ur blower resistor , but ur blower aint working at all so i would replace the blowerand the resistor cause they eventualy good out with when then the blower problems