AC Recharge

This procedure covers recharging the AC system on a 2016-2021 Honda Civic with 1.5L turbo engine, including leak testing, evacuation, and refilling with refrigerant and PAG oil.

Warnings

Tools required

Parts

• R-134a refrigerant × 1 — Use OEM specification
• PAG 46 oil for ND-11 compressor × 1 — Honda 38899-PYA-003 or equivalent
• AC system O-rings (if opening lines) × 1 — Use OEM specification

Fluids

• R-134a Refrigerant — 0.44 qt
• PAG 46 Compressor Oil — 0.1 qt

Preparation

1. Verify the AC compressor clutch engages when AC is turned on (if sufficient refrigerant remains). If no engagement, system may be empty.
2. Locate the low-pressure service port (larger cap, located on suction line near firewall) and high-pressure service port (smaller cap, on liquid line near condenser).
3. Start engine and allow to reach normal operating temperature with AC off.
4. Check underhood AC specification label for exact refrigerant and oil quantities for your specific model.
5. Ensure ambient temperature is above 60°F (15°C) for accurate charging and testing.

Procedure

1. 1

   Connect manifold gauges and check system pressure
   Turn off the engine and AC. Remove dust caps from both service ports. Connect the blue (low-pressure) hose to the low-pressure port and red (high-pressure) hose to the high-pressure port. Open both gauge valves and observe static pressure. If pressure is near zero, there is a significant leak. If pressure is present but low (below 30 psi), proceed with leak testing before recharging.
2. 2

   Recover existing refrigerant
   Connect the recovery machine to the manifold gauge set center port. Follow the recovery machine manufacturer's instructions to remove all remaining refrigerant from the system. Continue recovery until gauges show vacuum or the machine indicates recovery is complete. Allow at least 5 minutes after gauges reach vacuum to ensure complete recovery. Record the amount of refrigerant recovered for comparison to system capacity.
3. 3

   Perform leak test if low refrigerant was found
   If the recovered refrigerant was significantly less than system capacity (more than 2 oz low), inspect all AC line connections, condenser, evaporator, and compressor shaft seal for leaks. Use an electronic leak detector or add UV dye and pressurize with nitrogen to 150 psi maximum to locate leaks. Common leak points include compressor shaft seal, condenser front face (stone damage), and service port valves. Repair any leaks before proceeding.
4. 4

   Evacuate the AC system
   Connect the vacuum pump to the center port of the manifold gauge set. Open both manifold valves (low and high side). Start the vacuum pump and evacuate the system. Monitor the compound gauge (blue/low side) which should reach 29-30 inches of mercury (inHg) vacuum. Continue vacuum for minimum 30 minutes, or 45 minutes if any components were replaced or system was open to atmosphere. This removes all air and moisture from the system.
5. 5

   Perform vacuum hold test
   After evacuation time is complete, close both manifold valves and turn off the vacuum pump. Observe the compound gauge for 10 minutes. Vacuum should hold steady at 29-30 inHg. If vacuum drops more than 2 inHg, there is a leak or moisture in the system. Re-evacuate for another 30 minutes if slight vacuum loss occurs. If vacuum drops quickly, locate and repair leak before proceeding.
6. 6

   Add compressor oil if needed
   If components were replaced or significant oil was lost, add the appropriate amount of PAG 46 oil through the low-side service port: Add 2 oz if compressor was replaced, 1 oz if condenser replaced, 0.5 oz if evaporator replaced. If only recharging with no component replacement and normal amount of refrigerant was recovered, add 0.5-1.0 oz to compensate for oil trapped in recovery machine. Use only Honda-approved PAG 46 oil for the ND-11 compressor.
7. 7

   Charge the system with refrigerant
   Connect the refrigerant canister or tank to the center port of manifold gauge set through a refrigerant scale. Ensure the scale is zeroed. Open the refrigerant source valve. With engine off, open the low-side (blue) manifold valve only and allow liquid refrigerant to flow into the system until approximately half the total charge is added. The high side gauge should rise as refrigerant enters.
8. 8

   Complete charging with engine running
   Start the engine and set climate control to maximum cold, maximum fan speed, recirculation mode on. Once engine is running, turn on AC. The compressor clutch should engage within 30 seconds as system pressure rises. Continue adding refrigerant through the LOW side port only (never charge through high side with engine running). Add refrigerant slowly while monitoring gauges. Stop when total charge reaches specification (14-16 oz, verify on underhood label).
9. 9

   Monitor system pressures
   With engine at idle (800-900 RPM), AC on maximum cold, observe gauge readings. Target pressures at 80°F ambient: Low side should be 25-35 psi, high side should be 200-250 psi. At 90°F ambient: Low side 30-40 psi, high side 250-300 psi. If low side is too low (below 20 psi), add small amounts of refrigerant. If low side is too high (above 45 psi) or pressures are abnormal, system may be overcharged or have airflow restrictions.
10. 10

    Verify cooling performance
    Insert a thermometer into the center dash vent. With engine at 1500-2000 RPM, AC on maximum, recirculation on, the vent temperature should reach 38-45°F within 3-5 minutes at normal ambient temperatures (70-80°F). Temperature will be warmer at higher ambient temperatures. Compressor clutch should cycle on and off normally, or remain engaged continuously on models with variable displacement compressor.
11. 11

    Disconnect gauges and finalize
    Turn off the AC and engine. Close both manifold gauge valves. Quickly disconnect the low-side hose first, then high-side hose to minimize refrigerant loss (small amount of loss is normal). Immediately reinstall the dust caps on both service ports, tightening hand-tight plus 1/4 turn. Wipe any residual oil from service port area. Store manifold gauge set properly with hoses capped.

Reassembly

1. Ensure both service port caps are installed and hand-tight to prevent dirt and moisture entry.
2. If any AC line fittings were disconnected during leak repair, torque to specification using new O-rings lubricated with refrigerant oil.
3. Clean any spilled refrigerant oil from engine bay surfaces.

Verification

• Start the engine and turn AC to maximum cold. Compressor clutch should engage within a few seconds and remain engaged (or cycle normally if equipped with pressure switch).
• Verify center dash vent temperature reaches 38-45°F within 5 minutes at idle with recirculation on.
• Check that both AC lines near the firewall show appropriate temperature difference: suction line (low side, larger) should be cold to touch, liquid line (high side, smaller) should be warm.
• Listen for any unusual compressor noises, which could indicate insufficient oil or overcharge.
• Test drive the vehicle and verify AC maintains cold temperature under various engine speeds and loads.
• Inspect service ports and any repaired connections for signs of oil leakage after 24 hours of use.

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