When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
started about 3 months ago, sometimes it works sometimes it does not, makes no difference if the a/c or heater is on, or what speed the blower is set on. got in it today turned on the defrost blower did not work. got in it yesterday blower working fine.
I had the same symptoms, turned out to be the blower motor recepticle for the power connector. Turn it on high speed and have someone listen for the blower to kick on while you push and wiggle the connector. If it kicks on you have a bad blower motor.
Check the blower motor resistor, It is just to the drivers side of the blower motor in the engine compartment. It not unheard of for these to corrode and fail or for the connector to work loose. Remove the two screws and pull the resistor out to check its condition.
Check here for voltage from the speed selector switch.
I realize this is an old thread, but I have similar symptoms on my 2001 F-350 s 7.3L. Sometimes the blower will not come on, no matter what you do, if I'm running the truck for 20-30 minutes it will magically come on. There is no rhyme or reason as to when it works and when it doesn't.
I have changed the resistor (old one was fine, I think), checked the connections, etc.
I was wondering if the OP found a solution to his problem.