How do I Replace a complete a/c system on a Chevy 2004 trailblazer including compressor, dryer and condenser.

SOURCE: replace engine coolant sensor in '04 Trailblazer

http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800a1187

SOURCE: NEED TO REPLACE BLOWER RESISITOR. FAN ONLY WORKS ON HIGH SPEED

Under the dashboard on the passenger side you will see the blower motor. Near the blower motor inside the air duct is the resistor. It should be held in place by two screws. Hope this helps. Good luck

SOURCE: replace low beam headlight on 2003 chevy trailblazer

I just replaced the low-beam bulb on my 2003 Chevy Trailblazer. The grill just needs to be loosed slightly. Then, raise two L shaped brackets, one on each side. For the inside one, I needed to use a flathead screwdriver to get to it. The light assembly can then be pulled out. Remove the rubber cover and rotate the bulb one quarter turn left to release it. Pull out the bulb, replace with a new one ($11.50) from Advance Auto Parts, and reverse the process. Once I figured it out, took about 10 minutes total.

SOURCE: How do I replace the fuel filter in my 2004 Chevy

The filter is on the inner frame rail in front of the gas tank on the DRIVER'S side. You undo the rubber clip that holds the filter and pull the whole thing down so you can undo the clips for the input and output. Be careful to not mix these up. If you do, just follow the lines and see which way they go.
Don't release the fuel pressure (valve is inside the screw off cap) until you have pulled the filter down off of the frame, and have something ready to catch the small amount of gas that will come out.

SOURCE: 2004 chevy trailblazer fuse box diagrams

I have front and rear a/c. The air is blowing in the back but not in the front. Don I have 2 blowers/units. Could this be a fuse?