This procedure covers the replacement of the low-side AC hose on a 2014-2019 Toyota Corolla with 1.8L engine, including refrigerant recovery, hose removal, installation with new O-rings, and system recharge.

Warnings

Tools required

Parts

• AC low-side hose assembly × 1 — Use OEM specification
• AC line O-rings (multiple sizes) × 1 — 90301-10012 or equivalent
• PAG oil (ND-11 for Denso compressor) × 1 — Use OEM specification

Fluids

• R-134a refrigerant

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely if recently operated
3. Document refrigerant charge amount during recovery for proper refill
4. Have replacement O-rings and PAG oil ready before opening system
5. Review proper disposal procedures for old refrigerant oil

Procedure

1. 1

   Recover AC refrigerant
   Connect AC recovery machine to service ports. Follow machine manufacturer instructions to completely recover all refrigerant from the system. Record the amount of refrigerant recovered for recharge reference. Allow system to equalize to atmospheric pressure before proceeding.
2. 2

   Locate low-side AC hose
   Open hood and locate the low-side AC hose running from the accumulator/dryer (located near the passenger side of the engine bay) to the evaporator connection near the firewall. The low-side hose is the larger diameter hose of the two main AC lines.
3. 3

   Remove accumulator end fitting
   Using a flare nut wrench, carefully loosen the fitting connecting the low-side hose to the accumulator/dryer. Support the accumulator body with another wrench to prevent twisting. Once loose, separate the connection and remove the old O-ring. Cap or plug the accumulator port immediately to prevent contamination.
   ⚠Use flare nut wrenches to prevent rounding off the soft aluminum fittings. Standard wrenches will damage the fittings.
4. 4

   Remove evaporator end fitting
   Locate the connection point at the firewall where the low-side hose connects to the evaporator line. Use a flare nut wrench to loosen the fitting. On some models, you may need to remove a plastic cover or insulation to access this fitting. Once loose, separate the connection and remove the old O-ring. Cap or plug the evaporator port immediately.
5. 5

   Remove hose mounting brackets
   Remove any mounting clips or brackets securing the low-side hose to the body or engine. These are typically 10mm bolts or push-pin style clips. Note the routing path and bracket locations for proper reinstallation.
6. 6

   Extract old hose
   Carefully remove the old low-side hose from the vehicle, noting the exact routing path. Check for any additional clips or tie-downs that may still be securing the hose. Inspect the removed hose for signs of damage, abrasion, or oil leakage to identify the cause of failure.
7. 7

   Prepare new hose and O-rings
   Unpack the new low-side hose and verify it matches the original. Install new O-rings at both connection points on the hose. Lightly coat each new O-ring with clean PAG oil (ND-11) to ensure proper sealing and prevent damage during installation. Do not over-oil.
   ⚠Never reuse old O-rings. Always use new O-rings specifically designed for AC systems. Automotive O-rings are not compatible with refrigerant.
8. 8

   Route new hose
   Route the new low-side hose along the same path as the original, ensuring it does not contact sharp edges, hot components, or moving parts. The hose should have adequate clearance from the serpentine belt, exhaust manifold, and any suspension components. Reinstall any mounting brackets or clips.
9. 9

   Connect accumulator end
   Remove the cap from the accumulator port and inspect for contamination. Hand-thread the new hose fitting onto the accumulator connection, ensuring the O-ring seats properly. Once hand-tight, use a flare nut wrench and torque wrench to tighten to specification. Hold the accumulator body with a backup wrench to prevent rotation.
   Torque spec

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

    Connect evaporator end
    Remove the cap from the evaporator port and inspect for contamination. Hand-thread the new hose fitting onto the evaporator connection, ensuring the O-ring seats properly. Once hand-tight, use a flare nut wrench and torque wrench to tighten to specification. Support the evaporator line to prevent stress on internal components.
    Torque spec

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

    Add compressor oil charge
    Calculate the amount of PAG oil lost with the old hose (typically 1-2 oz for a hose replacement). Add the appropriate amount of fresh ND-11 PAG oil through the low-side service port using an oil injector tool. This compensates for oil removed with the old hose and oil absorbed by new components.
    ⚠Using incorrect PAG oil type or overfilling can damage the compressor. Verify ND-11 specification for Denso compressors used in this vehicle.
12. 12

    Evacuate AC system
    Connect vacuum pump to both service ports via manifold gauges. Open both gauge valves and evacuate the system for a minimum of 45 minutes, achieving at least 28" Hg vacuum. Close gauge valves and monitor vacuum for 10 minutes. If vacuum holds steady, system is sealed. If vacuum drops, locate and repair the leak.
13. 13

    Recharge AC system
    With system under vacuum, connect R-134a refrigerant supply to the low-side service port. Charge system with the amount of refrigerant documented during recovery (typically 15-18 oz for this vehicle). Follow refrigerant manufacturer instructions for proper charging procedure. Do not overcharge.
    ⚠Overcharging the AC system will reduce cooling performance and can damage the compressor. Charge only to the specified amount shown on the underhood label.

Reassembly

1. Reinstall any covers or panels removed for access
2. Verify all hose mounting brackets are secured and hose routing provides adequate clearance
3. Double-check both AC line fittings are torqued to specification
4. Ensure service port caps are reinstalled on both high and low-side ports

Verification

• Start engine and set AC to maximum cold with fan on high
• Monitor manifold gauges for proper pressure readings (low side: 25-35 PSI at idle, high side: 200-250 PSI at idle with 80°F ambient)
• Verify cold air output from vents (should reach 40-50°F with 80°F ambient temperature)
• Inspect both connection points for any signs of refrigerant oil leakage
• Use electronic leak detector or soap solution to verify no leaks at fittings
• Allow system to run for 10 minutes and recheck pressures and vent temperature
• Verify compressor cycles on and off normally and no unusual noises are present

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