Blower motor only runs on high

You probably need a blower motor resistor , it work's through a relay for high speed an resistors lower the speed for low , medium etc... Videos on youtube on how to test ! How to Install Replace Heater AC Fan Speed Resistor 99 07 Ford F250 F350...

Maxima.org will have it.

Check your blower motor resistor. It is commonly the part that the blower motor power connector plugs into. It sounds like the high speed element went first and you lost the high fan speed. If the remaining resistor element is broken, the fan will stop working. The resistor only have 2 elements; if they're both broken, it creates an open circuit to the blower.

If 1, 2 & 3rd speed not working, it is resistor (assuming you don't have EATC). High speed will work if fuse is ok and resistor is burned.
EATC = Electronci Auto Tem,p Control (Digital)

this problem is not caused by the switch, it is caused by a defective blower motor speed control resistor, the resistor is located near the blower motor.

it's your blower motor resistor in the plenum case. They usually blow the thermal limiter because the blower motor is drawing too much current. It's starting to go.
You can replace the resistor, 2 screws under the dash on the passenger side. It has a 4 or 5 wie connector. About $25 from a Ford or Mercury dealer.
Also go to the Villager site for more help.

http://groups.yahoo.com/group/villagerquest/

Hello Travis.
If yours is dual zone, I believe the resistor (blower control module) is a solid state. Did you check it using the fan speed selector and test the voltage output on the purple wire?
The gray black wire going into the resistor is a variable voltage output from the heater control panel. This signal is amplified by the resistor/blower control module.
The black wire out of the resistor also needs proper good ground.
There is a fuse in the underhood relay/fuse panel that feedback from the resistor output to the blower (purple wire) is also fed back to the heater control panel. Verify this fuse is good.

When blower motors go bad they will often absorb a lot of electrical current. This current has to go through the blower control/resistor and will often burn them out due to the heat developed from the high current load.
These resistors are also mounted in the airflow out of the fan motor to help cool them so if the fan is still drawing current and not blowing the resistor overloads and burns it out.
Not sure how you tested the resistor but I suspect yours is faulty.
If you would like more advise let me know.

KL

The resistor module,and the plug connector, and known problems in 1999-2006 blower motors for many GM trucks.

Did you also change the connector at the same time?

Here is a step-by-step check you can do to fix it. If you are only getting high speed (setting 5), then most likely you have a resistor problem, or the wiring connector to the resistor is bad. The ground wire prong being bad is a possible cause.

Check this for step-by-step checks:

http://www.sparkys-answers.com/2008/07/2005-chevrolet-silverado-blower-inop.html

There is a blower realy. Which steps the voltage up or down. If it fails it will run 12 volts or HIGH speed only... Replace that and your good.

heres the electrical diag.....