AC Accumulator

This procedure covers the removal and replacement of the A/C accumulator (receiver-drier) on a 2007 Ram 3500 with the 5.9L Cummins diesel engine, including refrigerant recovery and system recharge.

Warnings

Tools required

Parts

• A/C accumulator (receiver-drier) × 1 — Use OEM specification
• A/C line O-ring kit × 1 — Use OEM specification
• PAG oil for A/C system × 1 — PAG-46 or OEM specification

Fluids

• R-134a

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure engine is cool before beginning work
3. Verify A/C system has not been previously vented (if already empty, accumulator will need replacement regardless)
4. Gather all tools and replacement parts before starting
5. Note the amount of refrigerant recovered for proper recharge quantity

Procedure

1. 1

   Recover refrigerant from A/C system
   Connect A/C recovery machine to service ports (low-side port on accumulator, high-side on discharge line). Follow recovery machine instructions to completely evacuate all R-134a refrigerant from the system. Record the amount recovered for reference during recharge. Allow recovery machine to run until no additional refrigerant is detected.
2. 2

   Locate and access the accumulator
   Open the hood and locate the A/C accumulator. On the 5.9L Cummins, locate the A/C accumulator by tracing the A/C lines in the engine bay. It is a vertical cylindrical canister. Verify accessibility and remove any components necessary to reach the accumulator per the factory service manual.
3. 3

   Disconnect electrical connector
   Locate the pressure switch connector on top of the accumulator. Press the release tab and pull the connector straight off the switch. Move the wiring harness aside to prevent damage during accumulator removal.
4. 4

   Disconnect inlet line from accumulator
   The inlet line connects to the accumulator from the evaporator outlet (low/suction side). Verify against the factory service manual whether this system uses an accumulator/orifice-tube design. Use a backup wrench on the accumulator fitting while loosening the line nut with another wrench to prevent twisting the accumulator. Once loose, carefully separate the line and immediately cap or plug the open line to prevent contamination. Remove and discard the O-ring from the fitting.
5. 5

   Disconnect outlet line from accumulator
   The outlet line runs from the accumulator to the compressor. Use the same backup wrench technique to loosen the line connection at the bottom of the accumulator. Separate the line and cap/plug the opening. Remove and discard the O-ring. Some residual oil may drain from the accumulator.
6. 6

   Remove accumulator mounting bracket
   Locate the mounting bracket bolt(s) securing the accumulator to the body/frame. Typically this is a single bolt or clamp-style bracket. Remove the fastener(s) and retain for reinstallation. Note the orientation of any spacers or insulators.
7. 7

   Remove accumulator from vehicle
   Carefully lift the accumulator out of the mounting bracket. Keep it upright initially, then tip it to drain any remaining oil into a graduated container. Measure and record the amount of oil recovered. This will determine how much fresh oil to add to the new accumulator.
8. 8

   Prepare new accumulator
   Remove the new accumulator from packaging. Remove shipping caps from the inlet and outlet ports. Add the appropriate amount of fresh PAG oil to the new accumulator: use the same amount that was drained from the old unit, with a minimum of 2 oz. If no oil was recovered or measurement was not possible, add 3 oz of PAG-46 oil. Do not overfill.
9. 9

   Install new O-rings
   Install new O-rings on both the inlet and outlet fittings of the new accumulator. Lightly lubricate the O-rings with fresh PAG oil or refrigerant oil to ease installation and ensure proper seal. Do not use petroleum-based lubricants.
10. 10

    Install new accumulator
    Position the new accumulator into the mounting bracket, ensuring proper orientation (inlet/outlet ports align with their respective lines). Install the mounting bracket fastener(s) and tighten securely, but do not overtighten as this can distort the accumulator body.
11. 11

    Reconnect A/C lines
    Install new lubricated O-rings on both the inlet and outlet lines. Connect the inlet line from the evaporator to the top/side port of the accumulator. Hand-tighten first, then use wrenches with backup wrench technique to tighten securely. Repeat for the outlet line to the compressor. Ensure connections are snug but do not over-torque aluminum fittings.
12. 12

    Reconnect pressure switch
    Reconnect the electrical connector to the pressure switch on top of the accumulator. Ensure it clicks into place and is fully seated.
13. 13

    Evacuate A/C system
    Connect the A/C vacuum pump to the system service ports. Evacuate the system to 29+ inches of mercury vacuum for a minimum of 45 minutes (60 minutes recommended for this larger system). After evacuation, close valves and monitor vacuum for 10 minutes. If vacuum holds steady, system is leak-free. If vacuum drops, there is a leak that must be found and repaired.
14. 14

    Recharge A/C system
    Using the A/C manifold gauge set and charging equipment, recharge the system with R-134a refrigerant. Charge with the amount recovered in Step 1, or refer to the underhood A/C specification label for the exact factory-specified charge quantity for this vehicle. Charge into the low-side port only with engine running and A/C on MAX. Monitor pressures throughout charging process.
15. 15

    Check for leaks and verify operation
    With system charged, use electronic leak detector or soap solution to check all connections at the accumulator, especially the inlet and outlet fittings and pressure switch. Start engine and turn A/C to MAX. Verify compressor engages, system pressures are within specification (low side 25-40 psi, high side 200-300 psi at 75°F ambient), and cold air is produced at vents. Check temperature at center vent should be 40-50°F colder than ambient.

Reassembly

1. Ensure all A/C line connections are tight and properly sealed with new O-rings
2. Verify electrical connector to pressure switch is fully engaged
3. Double-check that accumulator is securely mounted in bracket

Verification

• Start engine and turn A/C to maximum cold with recirculation on
• Verify compressor clutch engages and remains engaged
• Check that center vent temperature reaches 38-45°F within 5 minutes of operation
• Verify no abnormal noises from compressor or system
• Check all fittings at accumulator for refrigerant leaks using leak detector
• Confirm low-side pressure is 25-40 psi and high-side is 200-300 psi at idle with 75°F ambient temperature
• Verify pressure switch connector is secure and system cycles properly

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