a/c problem on 2000 f150

I have a 2000 F-150 that the blower motor has stopped working on. I can every once in a while get it to work but only if I have been driving for a while. I was wondering if it might be the controls or some other problem? Pleasse help!!!!

Start by disconnecting the blower motor wiring harness. Run some jumper wires to the battery, and see if the motors ok. If the motors ok, check the relay in the power distribution center under the hood. The cover, or the owners manual, should tell you which one it is. I have changed quite a few of these lately. With it being so hot, and everyone running the ac on high, the contacts in the control box that it plugs into, get very hot. Sometimes hot enuff to oxidize the terminals, and cause intermittent contact. Also hot enuff to melt plastic, and make it hard to get out. Some of those motors draw almost 20 amps on high. If that checks ok, and youre getting power to the relay, and out of it, check the blower resistor. It should be mounted in the blower housing, between the blower motor, and the evaporator on that truck. It will have a 4 wire connector, and is held in place with 2 sheet metal screws. Check those things, and post back if you cant find the problem.

I checked everything that you said to check and it all seems to be in good shape. I have gotten it to work after driving for a while but not lately. I was wondering if maybe it could be a problem with the controls themselves.

Its possible it could be the dash switch, but they seldom go out. Try a couple other things first. Unhook the harness plug at the motor. Hook a test light to the brown wire with orange stripe( not sure about the color of the stripe, but the wire should be brown. The orange wire is from the resistor. Turn the key on. If the light doesnt come on, its the relay , or a fuse most likely. If it does come on , its either the resistor, or the dash switch. You can test the relay by switching it with another with the same part number. Theres always the possibility of damaged wires( we get alot of damage in this area from rats, mice and squirrels). If a radio has been installed/worked on, or something similar, the plug on the dash switch could have been knocked loose(it happens alot), and ive seen them not snapped in place tight enuff from the factory. If you have the climate control system, it could be the processor for that.

Try replacing the blower motor ,I have had a few that were itermitent internal thermal overload and cut out due to having dirt come in to motor from air over motor hose (that little hose going into motor from air(mix) box the way this happens is if you run your A/C on Max (pulling air from outside )
blower motor cost is bout 20-25 dollars ....,..

have you checked the grounds? you say it works after you have driven for awhile. thats odd but would indicate once things warm up(which would happen naturally after driving for awhile) it seems like the connection is made. normally things stop working when they warm up, ie.. cant pull in enough current for example due to pinched wire or something like that which would increase the resistance and lower the current flow. Remember, its the loss of current flow or reduction in current flow that causes a component not to work. you could still have the voltage but you wont have the correct current draw. you will need to check the current draw say like even jumping it from the battery(bypassing the blower motor circuit) dont see this being a fuse link or thermistor since those come into play when things get too hot. its very intermittent so you will have to just check all connections/grounds/relays etc in that circuit and make sure they are tight. Also, could check the switch too etc-basically all connections in the circuit. you may just hit the right bump and it starts working. good luck!

Unplug the power supply to the blower if you are getting 12v it is the motor.
if no voltage check a fuse or relay.