🔧 Impreza - A/C Compressor Replacement

Replacing the A/C compressor on your Impreza involves safely recovering the refrigerant, removing the drive belt and compressor, then installing the new compressor with new seals and recharging the system. This job is part mechanical and part HVAC service, and the A/C steps must be done correctly to avoid leaks and compressor failure.

Difficulty Level: Advanced | Estimated Time: 3-5 hours

Assumption: R-134a system; verify refrigerant/oil specs on under-hood label.

---

⚠️ Safety & Precautions

• ⚠️ Do not vent refrigerant to the air; have it recovered properly.
• ⚠️ Wear safety glasses and gloves; refrigerant can cause frostbite.
• ⚠️ Work on a cool engine; keep hands clear of belts and pulleys.
• ⚠️ Keep dirt out of A/C lines; cap/plug openings immediately.
• ⚠️ Disconnect the negative battery cable before unplugging the compressor.

---

🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• 10mm socket
• 12mm socket
• 14mm socket
• 3/8" drive ratchet
• 3/8" drive torque wrench (10-80 ft-lbs)
• Short extension (3")
• Serpentine belt tool (specialty)
• Trim clip removal tool
• Flathead screwdriver
• Line caps/plugs set (specialty)
• A/C manifold gauge set for R-134a (specialty)
• Vacuum pump (specialty)
• Refrigerant recovery machine (specialty)
• Refrigerant scale (specialty)
• PAG oil injector or measuring cup (specialty)
• Shop rags

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• A/C compressor - Qty: 1
• A/C compressor O-ring seal set - Qty: 1
• PAG A/C compressor oil (R-134a compatible) - Qty: 1
• R-134a refrigerant - Qty: 1 system charge
• A/C receiver/drier - Qty: 1 Recommended if compressor failed
• A/C expansion valve - Qty: 1 Recommended if compressor failed

---

📋 Before You Begin

• Park on level ground, set the parking brake, and chock the rear wheels.
• Have the refrigerant recovered with an A/C recovery machine (it removes refrigerant into a tank).
• Disconnect the battery using a 10mm socket (negative terminal first).
• If the old compressor failed loudly or seized, plan to replace the receiver/drier and consider flushing the system to prevent repeat failure.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Recover the refrigerant

• Use an A/C recovery machine (specialty) to recover the refrigerant from the high/low service ports.
• Confirm system pressure is at/near zero on the A/C manifold gauge set for R-134a (specialty) before opening any A/C lines.

Step 2: Raise the front of the car and remove splash shielding

• Use a floor jack (rated 2-ton minimum) to lift the front pinch weld/jacking point, then support with jack stands (rated 2-ton minimum).
• Remove the lower engine splash shield using a trim clip removal tool and 10mm socket.

Step 3: Remove the drive belt from the A/C compressor

• Use a serpentine belt tool (specialty) to rotate the belt tensioner and slip the belt off the A/C compressor pulley.
• Take a quick photo of belt routing.

Step 4: Unplug the compressor connector

• Release the electrical connector lock and unplug it by hand; use a flathead screwdriver gently only if needed.

Step 5: Disconnect the A/C lines from the compressor

• Place shop rags under the fittings to catch any oil residue.
• Remove the suction/discharge line retaining bolt(s) using a 12mm socket (varies by fitting style).
• Immediately cap the open lines and compressor ports using a line caps/plugs set (specialty).
• Remove and discard the old O-rings.
• Torque to 9-12 N·m (80-105 in-lbs) on line retaining bolt(s) during reassembly (verify exact spec for your fitting style).

Step 6: Remove the A/C compressor

• Support the compressor with one hand.
• Remove the compressor mounting bolts using a 12mm socket or 14mm socket (bolt head size can vary by bracket).
• Remove the compressor from underneath.
• Torque to 20-30 N·m (15-22 ft-lbs) on compressor mounting bolts during reassembly (verify exact spec for your bracket).

Step 7: Prep the new compressor (oil matching is critical)

• Drain and measure oil from the old compressor into a measuring cup (this tells you what to put back).
• Add the same amount of fresh PAG A/C compressor oil (R-134a compatible) into the new compressor using a PAG oil injector or measuring cup (specialty).
• Rotate the compressor hub by hand several turns to distribute oil (smooth, no binding).
• Too much oil can reduce cooling.

Step 8: Install the new compressor

• Position the compressor and start all mounting bolts by hand.
• Tighten mounting bolts using a torque wrench: Torque to 20-30 N·m (15-22 ft-lbs) (verify exact spec).
• Reconnect the electrical connector until it clicks.

Step 9: Reconnect A/C lines with new O-rings

• Install new O-rings from the A/C compressor O-ring seal set.
• Lightly lubricate O-rings with a dab of clean PAG A/C compressor oil using a gloved finger.
• Reinstall line retaining bolt(s) using a 12mm socket, then use a torque wrench: Torque to 9-12 N·m (80-105 in-lbs) (verify exact spec).

Step 10: Reinstall the drive belt

• Route the belt correctly and use the serpentine belt tool (specialty) to move the tensioner while you slip the belt onto the last pulley.
• Visually confirm the belt is fully seated in every pulley groove.

Step 11: Reinstall splash shielding and lower the car

• Reinstall the splash shield using a trim clip removal tool and 10mm socket.
• Lower the car safely from the jack stands using the floor jack.

Step 12: Evacuate and recharge the A/C system

• Reconnect the battery using a 10mm socket.
• Connect the A/C manifold gauge set for R-134a (specialty) to the low/high ports.
• Use the vacuum pump (specialty) to pull vacuum for at least 30 minutes, then close valves and verify it holds vacuum for 10-15 minutes.
• Recharge by weight using a refrigerant scale (specialty) with R-134a refrigerant to the exact amount on the under-hood A/C label.

---

✅ After Repair

• Start the engine and turn A/C on MAX; confirm the compressor clutch engages and the radiator fans operate.
• Check vent temperature and listen for abnormal noise.
• Inspect all A/C fittings for oily residue that could indicate a leak.
• If cooling is weak or pressures are abnormal, stop and re-check charge amount and O-ring seating.

---

💰 DIY vs Shop Cost

Shop Cost: $900-$1,600 (parts + labor + evac/recharge)

DIY Cost: $250-$700 (parts only, if you already have HVAC equipment)

You Save: $400-$1,100 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5-4.0 hours.

---

🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.