AC Hose - Low Side

This procedure covers replacement of the low-side AC hose on a 2019-2024 Toyota RAV4 with 2.5L I4 engine, including refrigerant recovery, hose replacement, and system recharge.

Warnings

Tools required

Parts

• AC low-side hose assembly × 1 — Use OEM specification
• AC line O-rings × 4 — Use OEM specification
• R-134a refrigerant × 1 — Typically 18-22 oz for system
• PAG oil ND-11 (for replacement) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely if recently operated
3. Verify AC system type - this procedure is for R-134a systems only
4. Connect AC recovery machine and verify system pressure before beginning work
5. Gather all replacement parts and verify correct low-side hose for your specific RAV4 configuration
6. Prepare clean workspace and lay out new O-rings with PAG oil applicator ready

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to service ports. Follow machine instructions to completely recover all refrigerant from the system. Verify system pressure reads zero before proceeding. Record amount of refrigerant and oil removed for recharge reference.
   ⚠️Ensure complete refrigerant recovery before disconnecting any AC lines. System may still contain residual pressure.
2. 2

   Access engine compartment and locate low-side hose
   Open hood and secure with prop rod. The low-side AC hose runs from the accumulator/dryer near the firewall to the compressor on the passenger side of the engine. Identify both connection points - one at the accumulator and one at the evaporator inlet near the firewall. Note routing and any clips securing the hose.
3. 3

   Remove plastic engine covers if equipped
   Remove any plastic engine covers that restrict access to the AC lines. Covers are typically secured with push clips or small bolts. Set covers aside in a clean area.
4. 4

   Disconnect low-side hose at compressor connection
   Locate the low-side line connection at the compressor (larger diameter line). Use a flare nut wrench or box-end wrench to loosen the fitting. Turn counterclockwise to disconnect. Cap or plug the compressor port immediately to prevent moisture and debris entry. Remove and discard old O-rings from the connection.
   ⚠Residual refrigerant or oil may drain from the line. Have a rag ready to catch any drips.
5. 5

   Disconnect low-side hose at evaporator connection
   Locate the connection point near the firewall where the low-side hose connects to the evaporator inlet line. Loosen and remove the line fitting. Cap or plug the evaporator line immediately. Remove and discard old O-rings from this connection as well.
6. 6

   Remove hose mounting clips and extract hose
   Release any plastic clips or brackets securing the low-side hose to the engine or chassis. Note the routing path carefully. Carefully extract the hose from the engine compartment, taking care not to damage surrounding components or wiring.
7. 7

   Prepare new hose and O-rings
   Unpack new low-side hose and verify it matches the old hose configuration. Install new O-rings on all four connection points (two on each end of the new hose). Apply a thin coat of fresh PAG oil ND-11 to each O-ring to ensure proper sealing and prevent damage during installation. Add approximately 1-2 ounces of PAG oil into the new hose to replace oil lost with old hose.
   ℹ️Use only the specified PAG oil type for Toyota AC systems. Do not use PAG oil from other manufacturers as viscosity may differ.
8. 8

   Route and position new low-side hose
   Route the new hose through the engine compartment following the exact path of the original hose. Ensure the hose does not contact hot engine components, sharp edges, or moving parts. Position both ends at their respective connection points but do not tighten yet.
9. 9

   Connect and torque evaporator end fitting
   Remove the cap from the evaporator line. Verify O-rings are properly seated and lubricated. Hand-thread the fitting clockwise until snug, then use a torque wrench to tighten to specification. Ensure the hose is not twisted or kinked.
   Torque spec

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

    Connect and torque compressor end fitting
    Remove the cap from the compressor port. Verify O-rings are properly seated and lubricated. Hand-thread the fitting clockwise until snug, then use a torque wrench to tighten to specification. Double-check that the hose routing allows for engine movement without stress on the connections.
    Torque spec

    AC Line Fittings20 Nm (15 lb-ft)
11. 11

    Secure hose with mounting clips
    Reinstall all mounting clips and brackets that secure the low-side hose to the engine or chassis. Ensure the hose is properly supported and cannot vibrate against other components.
12. 12

    Evacuate AC system
    Connect AC service machine to the system. Run a deep vacuum (minimum 500 microns) for at least 30-45 minutes to remove all air and moisture from the system. Monitor vacuum hold - system should hold vacuum without rise for at least 10 minutes after pump is shut off. If vacuum does not hold, check all connections for leaks.
    ⚠Proper evacuation is critical. Moisture in the system will cause compressor damage and poor cooling performance.
13. 13

    Recharge AC system with refrigerant
    Using the AC service machine, recharge the system with the appropriate amount of R-134a refrigerant (typically 18-22 oz total - verify exact specification on underhood label). Add refrigerant according to machine instructions. Account for the PAG oil already added to the new hose when calculating total oil charge.
14. 14

    Reinstall engine covers and verify installation
    Reinstall any plastic engine covers removed earlier. Check that all tools have been removed from the engine compartment. Verify all AC line connections are properly torqued and secure.

Reassembly

1. All AC line fittings must be torqued to specification with new O-rings installed
2. Hose routing must match factory configuration to prevent contact with hot or moving components
3. System must be properly evacuated before recharging to prevent moisture contamination
4. Total refrigerant charge must match the specification on the underhood AC label

Verification

• Start engine and turn AC to maximum cooling with fan on high
• Verify compressor engages (clutch clicks and pulley spins)
• Check that cold air is produced from vents within 2-3 minutes
• Monitor AC pressure gauges - low side should read 25-45 PSI, high side should read 150-250 PSI at idle with ambient temperature 70-80°F
• Inspect all new connections for signs of refrigerant leaks (oil residue or frost formation)
• Use electronic leak detector or soap solution to verify no leaks at new hose connections
• Verify hose does not contact engine components or vibrate excessively during engine operation
• Test AC performance during a road test to ensure adequate cooling under load

More procedures for this vehicle