AC Hose Assembly

Replace the AC hose assembly on a 1994-2007 Dodge Ram 2500 with 5.9L Cummins diesel engine, including refrigerant recovery, hose removal/installation, and system recharge.

Warnings

Tools required

Parts

• AC hose assembly (specify suction, discharge, or liquid line) × 1 — Use OEM specification
• AC line O-rings (various sizes) × 4 — Use OEM specification
• R-134a refrigerant × 1 — Approximately 2.2 lbs total system capacity
• PAG 46 oil for AC system × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine to cool completely if recently operated
3. Identify which AC hose assembly requires replacement (suction line, discharge line, or liquid line from condenser to evaporator)
4. Verify replacement hose matches original routing and fitting types
5. Ensure AC recovery machine is properly calibrated and has adequate tank capacity

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to service ports on the AC system. Follow recovery machine instructions to completely evacuate all R-134a refrigerant from the system. Record the amount of refrigerant recovered for recharge reference. Verify system pressure reaches 0 psi on manifold gauges before proceeding.
2. 2

   Access the damaged AC hose
   For suction/discharge lines at compressor: Remove engine cover if equipped. For lines near firewall: Access may require removing battery or air intake components. For lines at condenser: Access from front of vehicle, may require partial grille or fan shroud removal. Trace the complete hose routing to identify all mounting brackets and connection points.
3. 3

   Disconnect AC hose at compressor end
   Using line wrenches to prevent rounding, loosen the AC line fitting at the compressor. Support the compressor-side connection to avoid stressing the compressor ports. Once loose, carefully unthread the fitting by hand and separate the connection. Immediately cap or plug the open compressor port to prevent contamination. Remove and discard the old O-rings from the fitting.
   ⚠Use line wrenches (flare nut wrenches) instead of open-end wrenches to avoid damaging the soft aluminum fittings.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
4. 4

   Disconnect AC hose at opposite end
   Depending on which hose is being replaced, disconnect at condenser, evaporator, or accumulator/drier. Use line wrenches and support the stationary component to avoid stress. Remove the connection and immediately cap or plug both openings. Remove and discard old O-rings. Note the routing of any support brackets or clips.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
5. 5

   Remove hose mounting brackets
   Disconnect any mounting brackets or clips securing the AC hose to the chassis, engine, or body. On Cummins-equipped trucks, hoses typically route along the passenger side of engine bay. Remove any zip ties or support clips. Carefully extract the old hose assembly, noting the exact routing path for new hose installation.
   Torque spec

   Mounting Bracket Bolts24 Nm (18 lb-ft)
6. 6

   Prepare new AC hose assembly
   Unpack new AC hose assembly and verify it matches the original in length, fitting types, and routing bends. Install new O-rings on both ends of the new hose (do not reuse old O-rings). Lightly coat new O-rings with fresh PAG 46 oil to ensure proper sealing and prevent tearing during installation. Keep O-rings clean and free of debris.
7. 7

   Route new AC hose assembly
   Route the new hose assembly following the exact path of the original hose. Ensure the hose does not contact any sharp edges, hot exhaust components, or moving parts like belts or pulleys. On the Cummins diesel, verify clearance from turbocharger and exhaust manifold. Loosely install any mounting brackets or support clips to hold routing position.
8. 8

   Connect hose at compressor
   Remove cap from compressor port. Verify new O-ring is properly seated in the hose fitting groove and lightly oiled. Hand-thread the fitting onto the compressor port, ensuring it threads smoothly without cross-threading. Once hand-tight, use a torque wrench to tighten to specification. Support the compressor body to avoid stressing the mounting.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
9. 9

   Connect hose at opposite end
   Remove cap from the condenser, evaporator, or accumulator port. Verify O-ring is properly seated and oiled. Hand-thread the fitting, ensuring smooth engagement without cross-threading. Torque to specification using a torque wrench. Verify both connections are secure and O-rings are not pinched or damaged.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
10. 10

    Secure mounting brackets
    Tighten all mounting brackets and support clips to secure the AC hose in its routed position. Verify the hose has no kinks, tight bends, or contact with hot or moving components. Ensure adequate clearance for vibration and thermal expansion during operation. Double-check all mounting hardware is tight.
    Torque spec

    Mounting Bracket Bolts24 Nm (18 lb-ft)
11. 11

    Add refrigerant oil to system
    Calculate the amount of PAG 46 oil to add based on the amount lost during hose removal (typically 1-2 oz for hose replacement). Add the appropriate amount of fresh PAG oil through the low-side service port using an oil injector tool. This compensates for oil lost with the old hose and any oil removed during recovery.
12. 12

    Evacuate AC system
    Connect vacuum pump to AC service ports using manifold gauge set. Evacuate the system to at least 29 inches Hg (500 microns preferred) and hold vacuum for minimum 30 minutes. Monitor for vacuum decay which indicates a leak. If vacuum holds steady, the system is ready for recharge. If vacuum decays, locate and repair leak before proceeding.
13. 13

    Recharge AC system
    Using the refrigerant recovery/recharge machine or manifold gauges with refrigerant tank, charge the system with R-134a to the factory specification listed on the underhood AC charge label (adjust based on amount recovered). Charge through the low-side port with engine off initially, then complete charging with engine running and AC on MAX. Monitor pressures on manifold gauges to verify proper charge level.

Reassembly

1. Reinstall any components removed for access (battery, air intake, grille, fan shroud, engine cover)
2. Verify all AC line connections are tight and properly torqued
3. Ensure no tools or shop towels were left in engine bay

Verification

• Start engine and turn AC to MAX cold with blower on high
• Verify cold air discharge from vents within 2-3 minutes of operation
• Check AC system pressures with manifold gauges: low side should be 25-45 psi, high side 200-300 psi at idle (ambient dependent)
• Inspect all AC line connections for signs of refrigerant oil leakage
• Use leak detector or UV light (if dye was added) to verify no leaks at new hose connections
• Verify AC compressor clutch engages and disengages properly without unusual noise
• Test AC performance over 15-20 minute drive cycle to ensure consistent cooling

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