If the Heating A/C fan only works in certain positions ie. 3&4 but not 1 or 2. You most likely need a new blower motor resistor.Google+
Car Problem Reports
Dodge Stratus Heating & Air Conditioning Fan unit only works in certain positions
Dodge Stratus Problem
Average Mileage: 102,633 mi (45,000 mi - 160,000 mi)
Visitor, 2005 Dodge Stratus, 138,225 mi
Fan only works on Nbr 4 setting there is a video about it with clear details how easy it is to change the Fan Resistor....the part is $18.50 or so at NAPA Auto Parts...easy fix I think I will try it myself :) I am 51 yr old woman with no mechanical skills video shows you just need 8 mm socket with extension and flash light. Removing part is not hard it appears on the video from www.1AAuto.com
Visitor, 2002 Dodge Stratus, 140,000 mi
its a blower motor resistor under $50 for part and takes 15 minutes to do it yourself
Visitor, 2002 Dodge Stratus, 82,596 mi
The A/C and heater only work on the high setting. Settings 1, 2, & 3 dont work
A/C & heater does not work on settings 1&2 only work on 3&4.
Air Conditioner/ Heat Switch only works on high setting.