Blower Motor Gone Crazy

Guys, I haven't seen anything on this site exactly describing the problem my 2001 Crown Vic has. The air conditioner cools great. The problem is, after I have driven for approx. 30 min., the blower motor will go to full speed. Sometimes this last for only a few seconds, then it returns to normal. It may cycle from fast to slow back and forth for several minutes. Then, it may work normal for a while and just go crazy every once in a while.

I heard that on a 2004 it could be the blower motor resistor. This is suppose to be either in the firewall housing or behind the glove box. I did not find one on my 2001. A local auto parts dealer said he did not list a resistor for that model.

Can anyone save me an expensive trip to the shop?

do you have eatc(eletronic temp control) or is it manual(standard)?

I have a button marked "AUTOMATIC" and there is also a thumb wheel manual fan control. When it is having one of it's spells, the manual control will not override it.

Make a trip to the dealer parts department,and ask for a resistor for the unit.
Then ask to see the parts diagram showing you where its located. They have a screen like a computer that they put in microfilm it will show a picture.
If your trying to save money make a trip to a scrap yard watch the parts puller remove it for you then you will know where its located. Usually their close to the blower motor on the housing for the heater core. They might let you go look and remove it. Much easier in a junk yard as you aren't as careful.
If you have climate control you might to buy a manual. http://www.alldata.com/ buy a years subscription
appx.$25.00 print all electrical diagrams before it expires.