If you're determined to do it yourself, here's a general overview. This is NOT a complete guide, and you should consult a repair manual specific to your 2002 Chevy Trailblazer for detailed instructions and diagrams.
1. Safety First:
* Refrigerant Recovery: This is CRUCIAL. Automotive AC refrigerant (R-134a) is harmful to the environment and your health. You MUST use a refrigerant recovery machine to safely evacuate the refrigerant from the system before disconnecting any lines. This is not a DIY-able step unless you own and know how to properly operate such a machine. Improper handling can result in fines and environmental damage.
* Eye Protection: Wear safety glasses at all times.
* Gloves: Wear work gloves to protect your hands.
* Proper Ventilation: Work in a well-ventilated area.
2. Preparation:
* Consult a Repair Manual: Obtain a repair manual specific to your 2002 Chevy Trailblazer. This will provide detailed instructions, diagrams, torque specifications, and other vital information.
* Gather Tools: You'll need a variety of tools, including wrenches, sockets, a refrigerant recovery machine, AC line wrenches (to avoid damaging the fittings), a compressor oil charging fitting (if not already on the new compressor), and possibly a vacuum pump to evacuate the system after the repair.
3. Removal of the Old Compressor:
* Disconnect the Battery: Disconnect the negative battery terminal to prevent electrical shorts.
* Recover Refrigerant: Use the refrigerant recovery machine to safely remove all refrigerant from the system.
* Disconnect AC Lines: Carefully disconnect the high-pressure and low-pressure lines from the compressor using the correct AC line wrenches. Note the position and orientation of each line.
* Disconnect Electrical Connector: Disconnect the electrical connector from the compressor clutch.
* Remove Mounting Bolts: Remove the bolts securing the compressor to the engine block or mounting bracket.
* Remove Compressor: Carefully remove the old compressor.
4. Installation of the New Compressor:
* Install New O-Rings: Install new O-rings on the high and low-pressure lines before connecting them to the new compressor.
* Install Compressor: Carefully install the new compressor, ensuring it's properly seated and aligned.
* Tighten Mounting Bolts: Tighten the mounting bolts to the manufacturer's specifications (found in your repair manual).
* Connect Electrical Connector: Connect the electrical connector to the compressor clutch.
* Connect AC Lines: Carefully connect the high and low-pressure lines to the new compressor, ensuring the connections are tight and secure.
* Add Compressor Oil: Some compressors require the addition of compressor oil; refer to your repair manual or the new compressor's instructions for the correct amount and type of oil.
5. System Evacuation and Charging:
* Evacuate the System: Use a vacuum pump to evacuate the system for a specified period (usually at least 30 minutes) to remove any air and moisture.
* Recharge with Refrigerant: Use the refrigerant charging machine to recharge the system with the correct amount of R-134a refrigerant. This step usually involves a careful process following the instructions on the charging machine. Too much or too little refrigerant can damage the system.
6. Testing and Final Steps:
* Test the System: Turn on the AC system and check for proper cooling and leaks.
* Reconnect Battery: Reconnect the negative battery terminal.
Again, I strongly recommend seeking professional help from a qualified mechanic. Improper handling of refrigerants can be dangerous, and mistakes can lead to costly repairs. The steps above are a simplified overview and don't cover all the nuances involved in this complex repair. Refer to your vehicle's repair manual and consider consulting a professional for assistance.
