AC Hose - Low Side

This procedure removes and replaces the low-side AC hose on a 1992 Dodge Viper 8.0L V10. System must be evacuated by a certified technician before beginning work.

Warnings

Tools required

Parts

• AC low-side hose assembly × 1 — Mopar 04734542 or equivalent
• AC line O-ring kit (assorted sizes) × 1 — Use OEM specification for R-12 compatibility

Fluids

• ac_refrigerant
• PAG oil for AC system — 0.25 qt

Preparation

1. Have AC system evacuated and refrigerant recovered by a certified technician with proper recovery equipment
2. Verify system is completely depressurized before beginning work
3. Raise front of vehicle and support securely on jack stands
4. Allow engine to cool completely if recently operated
5. Prepare clean workspace for disconnected fittings to prevent contamination

Procedure

1. 1

   Locate low-side AC hose routing
   The low-side AC hose runs from the evaporator outlet (near the firewall on the passenger side) to the compressor suction port on the front-mounted AC compressor. Trace the hose routing to identify all mounting brackets and connection points. The low-side hose is typically the larger diameter line of the two AC hoses.
2. 2

   Disconnect low-side hose at evaporator
   Working from under the vehicle or through the engine bay (access from passenger side), locate the evaporator outlet connection at the firewall. Use a line wrench to loosen the fitting at the evaporator outlet. Hold the evaporator fitting stationary while turning the hose fitting to prevent damage. Once loose, carefully remove the hose end and immediately cap or cover the evaporator port with a clean shop towel to prevent contamination. Inspect and discard the old O-rings.
3. 3

   Disconnect low-side hose at compressor
   Locate the suction port on the AC compressor (front of engine); verify compressor mounting location against factory service documentation. This is the larger of the two compressor connections. Use a line wrench to loosen the fitting at the compressor suction port. Hold the compressor port fitting stationary while turning the hose fitting counterclockwise to loosen (standard right-hand thread). Remove the hose end and cap or cover the compressor port with a clean towel. Inspect and discard the old O-rings.
4. 4

   Release mounting brackets
   The low-side hose is secured to the vehicle with mounting brackets along its length. Identify and remove the bracket mounting bolts securing the hose. There are typically 2-3 brackets depending on routing. Use a socket or wrench to remove the bracket bolts, keeping track of all hardware for reinstallation.
   Torque spec

   Mounting Bracket Bolts24 Nm (18 lb-ft)
5. 5

   Remove low-side hose assembly
   With all connections and brackets released, carefully remove the low-side hose assembly from the vehicle. Note the exact routing path and any clearances required during removal to ensure proper installation of the replacement hose. Inspect the removed hose for signs of damage, chafing, or the cause of failure.
6. 6

   Prepare new O-rings
   Remove all old O-rings from both the evaporator outlet port and compressor suction port using a pick tool. Clean the sealing surfaces with a lint-free shop towel. Select the correct size new O-rings from the kit and coat them generously with fresh PAG oil (R-134a system). Install new O-rings onto the evaporator and compressor ports, ensuring they seat properly in their grooves.
7. 7

   Prepare new hose assembly
   Unpack the new low-side hose assembly and verify it matches the removed part in length, fitting types, and routing configuration. Remove protective caps from the hose ends. Install new O-rings onto both ends of the new hose and coat them with fresh PAG oil. Add approximately 1 oz of fresh PAG oil into the hose assembly to replace oil lost during service.
8. 8

   Route new hose assembly
   Following the same path as the original hose, route the new low-side hose assembly from the compressor area to the evaporator outlet. Ensure the hose does not contact any sharp edges, hot exhaust components, or moving parts. Verify adequate clearance from the engine and accessories throughout the routing path.
9. 9

   Install mounting brackets
   Position the hose in its mounting brackets and loosely install the bracket mounting bolts. Do not fully tighten yet to allow final positioning adjustment. Ensure the hose sits naturally in the brackets without tension or kinking.
   Torque spec

   Mounting Bracket Bolts24 Nm (18 lb-ft)
10. 10

    Connect hose at evaporator
    Position the hose end at the evaporator outlet port. Hand-thread the fitting carefully to avoid cross-threading. Once hand-tight, use a line wrench to tighten the fitting to specification while holding the evaporator port stationary to prevent damage.
    Torque spec

    AC Line Fittings27 Nm (20 lb-ft)
11. 11

    Connect hose at compressor
    Position the hose end at the compressor suction port. Hand-thread the fitting carefully to avoid cross-threading. Once hand-tight, use a line wrench to tighten the fitting to specification while holding the compressor port stationary.
    Torque spec

    AC Line Fittings27 Nm (20 lb-ft)
12. 12

    Final bracket adjustment and torque
    With both ends connected, verify the hose routing is correct with no interference or tension. Adjust bracket positions as needed for optimal support. Torque all mounting bracket bolts to specification.
    Torque spec

    Mounting Bracket Bolts24 Nm (18 lb-ft)
13. 13

    Verify installation clearances
    Perform a final inspection of the installed hose. Verify adequate clearance from exhaust manifolds, engine block, and all moving components. Check that the hose is properly supported along its entire length and does not contact sharp edges. Verify both fittings are properly torqued and show no signs of cross-threading.

Reassembly

1. Lower vehicle from jack stands
2. Have the AC system evacuated, leak-tested, and recharged by a certified technician with proper equipment
3. The system should be evacuated for at least 30 minutes to remove moisture before recharging
4. Verify proper refrigerant charge quantity per manufacturer specifications
5. Test AC system operation and verify cold air output before returning vehicle to service

Verification

• Start engine and allow AC system to stabilize; verify compressor engages when AC is activated
• Check all line connections for refrigerant leaks using electronic leak detector or approved leak detection method
• Verify low-side pressure is within normal operating range (typically 25-35 psi at idle with system stabilized)
• Inspect hose routing visually with engine running; confirm no contact with moving parts or excessive vibration
• Test AC cooling performance at dash vents; temperature should drop to approximately 40-50°F within 5 minutes of operation

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