Here's a general outline of the process:
1. Safety Precautions:
* Refrigerant Recovery: This is absolutely crucial. The refrigerant in your AC system 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. Improper handling is illegal and can result in fines.
* Eye Protection: Wear safety glasses or goggles throughout the process.
* Gloves: Wear gloves to protect your hands from sharp edges, dirt, and potentially oily components.
* Disconnect the Battery: Disconnect the negative (-) battery terminal to prevent electrical shorts.
2. Accessing the Evaporator:
* This involves significant disassembly. Expect to remove:
* The dashboard (at least partially, possibly completely depending on the model).
* Possibly the glovebox.
* Possibly the steering column.
* Possibly other interior components to gain access to the HVAC housing containing the evaporator core. The extent of this will depend heavily on your specific truck model.
* Consult your repair manual for the specific steps to disassemble your dashboard and gain access.
3. Removing the Old Evaporator:
* Once you have access to the evaporator, you'll need to disconnect:
* The refrigerant lines (after evacuation). These are often sealed with O-rings, which must be replaced with new ones.
* The drain tube.
* The electrical connections (if any).
* Carefully remove the evaporator core from its housing. This may involve removing screws or clips.
4. Installing the New Evaporator:
* Install the new evaporator core, ensuring it's properly seated.
* Reconnect the drain tube, refrigerant lines (using new O-rings), and electrical connections.
* Carefully reassemble the dashboard and other components you removed.
5. Recharging the AC System:
* After reassembly, you'll need to recharge the AC system with the correct amount and type of refrigerant using a refrigerant charging machine. The amount required will be specified in your repair manual. You will also need to add PAG oil as needed.
6. Testing:
* After recharging, test the AC system to ensure it's working correctly. Look for leaks, proper cooling, and adequate airflow.
Critical Considerations:
* Repair Manual: A factory repair manual specific to your 1999 Dodge truck is indispensable. It will provide detailed instructions, diagrams, torque specifications, and other vital information.
* Special Tools: You'll likely need specialized tools, such as refrigerant recovery and charging equipment, various sockets and wrenches, possibly a dashboard removal tool kit.
* Experience: This is an advanced repair. If you lack experience working on automotive AC systems, it's strongly recommended that you take it to a qualified professional. Improper handling of refrigerant can be dangerous and costly. Improper reassembly can lead to further damage.
This is a complex procedure. Attempting it without the proper knowledge, tools, and experience could cause significant damage to your vehicle and potentially put you at risk. If you are unsure about any aspect of this process, consult a qualified mechanic specializing in automotive air conditioning.
