Complete replacement of the air conditioning hose assembly on a 1966 Chevrolet Corvette 327ci V8, including refrigerant recovery, hose removal, installation of new hoses, and system recharge.

Warnings

Tools required

Parts

• AC hose assembly kit (compressor to condenser, evaporator lines) × 1 — Use OEM specification or quality aftermarket equivalent
• O-ring assortment for AC fittings × 1 — Use correct size for R-12 or R-134a conversion
• AC compressor oil × 1 — R-12 mineral oil or PAG oil for R-134a conversion
• Refrigerant (R-12 or R-134a) × 1 — Typically 2.5-3 lbs for factory system
• UV leak detection dye (optional) × 1 — Compatible with refrigerant type

Preparation

1. Park vehicle on level surface and engage parking brake
2. Verify refrigerant type by checking service port fittings and any conversion labels under hood
3. Allow engine to cool completely if recently operated
4. Prepare AC recovery machine and verify it is properly maintained and certified
5. If working on passenger side or underneath, raise and support vehicle on jack stands as needed for access
6. Identify all AC hose routing before removal - take photos for reference during reinstallation

Procedure

1. 1

   Recover refrigerant from system
   Connect manifold gauge set to high and low side service ports. Connect recovery machine to center port of manifold gauges. Open both manifold valves and start recovery machine. Follow manufacturer instructions for complete refrigerant recovery. Recovery is complete when both high and low side gauges read 0 psi or in vacuum for at least 5 minutes with machine running. Close manifold valves and disconnect recovery machine. This system's original R-12 refrigerant capacity should be verified against the factory service manual before recovery (commonly in the range of approximately 2.5-3 lbs for factory systems of this era).
2. 2

   Disconnect battery ground cable
   Using appropriate wrench, loosen and remove the negative battery cable from battery terminal. Isolate cable away from battery to prevent accidental reconnection during work.
3. 3

   Remove compressor hose connections
   Locate the AC compressor on the front driver side of the engine. Using flare nut wrenches to prevent rounding, disconnect the discharge line (high pressure) and suction line (low pressure) from the compressor. Note the fitting sizes on the discharge (high pressure) and suction (low pressure) lines and use the correctly sized flare nut wrench for each; verify against factory service manual specifications before assuming sizes. Have catch pan ready as residual oil will drain from connections. Cap all open fittings immediately with plugs or tape to prevent moisture and debris entry.
4. 4

   Disconnect condenser hose connections
   Access the condenser mounted in front of the radiator. Disconnect the liquid line from the condenser outlet (lower connection) using appropriate flare nut wrench. Disconnect the discharge line from condenser inlet (upper connection). Cap all open fittings immediately. Note the routing of hoses through the engine bay for reinstallation.
5. 5

   Disconnect evaporator hose connections at firewall
   From inside engine bay, locate the evaporator lines passing through the firewall on passenger side. Disconnect the liquid line feeding the evaporator and the suction line returning to compressor at their firewall connections. These connections may be difficult to access - work carefully to avoid damaging surrounding components. Cap all open fittings.
6. 6

   Remove hose mounting brackets and clips
   Locate and remove the AC hose mounting brackets securing hoses along their routing path (verify exact count and locations against factory documentation). Typical locations are on the inner fender, along the frame rail, and near the firewall. Remove any metal or plastic clips holding hoses to other lines or chassis components. Keep all hardware organized for reinstallation.
7. 7

   Remove old hose assembly from vehicle
   Carefully extract the complete hose assembly from the engine bay, working hoses through their routing path. Note any tight clearances or specific routing required to clear engine components, steering linkage, and frame rails. If hoses are severely deteriorated or stuck, may require careful cutting to remove, but preserve fittings if possible for reference.
8. 8

   Inspect and clean all connection points
   Thoroughly inspect all male fittings on compressor, condenser, and firewall connections for damage, corrosion, or debris. Clean threads and sealing surfaces with wire brush. Inspect for any signs of previous leaks indicated by oil residue. Replace any damaged fittings before proceeding. Check that all caps remain on open ports to keep system sealed.
9. 9

   Prepare new hose assembly
   Unpack new hose assembly and verify all hoses are included and match original routing. Install new O-rings on all male fittings - discard old O-rings. Lightly coat new O-rings with appropriate AC compressor oil (mineral oil for R-12, PAG oil for R-134a). Do not over-oil as this will contaminate the system. If using UV dye, add appropriate amount to compressor oil before installation.
10. 10

    Route and install new hose assembly
    Beginning at the compressor, route new hoses through engine bay following original path documented in photos. Ensure hoses have adequate clearance from exhaust manifolds (minimum 2 inches), moving components like belts and pulleys, and sharp edges. Connect the discharge line to the compressor, then the suction line, using the correctly sized flare nut wrenches. Tighten each fitting to the factory-specified torque value (verify in service manual) — do not over-tighten.
11. 11

    Connect hoses to condenser
    Route discharge line to condenser inlet (upper) and connect using flare nut wrench, tightening to factory-specified torque. Route liquid line to condenser outlet (lower) and connect using the same method. Verify hoses are not twisted and have smooth bends without kinks. AC hose fittings use captured O-rings and should not be over-tightened.
12. 12

    Connect evaporator lines at firewall
    Working from engine bay side, connect liquid line and suction line to evaporator ports at firewall. Use appropriate wrench sizes and tighten each fitting to the factory-specified torque value. Double-check that correct lines are connected to correct ports - liquid line (smaller diameter) to inlet, suction line (larger diameter) to outlet.
13. 13

    Install mounting brackets and secure hoses
    Reinstall all mounting brackets removed earlier, securing hoses at proper locations to prevent vibration and contact with other components. Install all clips to hold hoses in position. Ensure no hose is under tension or compressed, and all have natural curves. Verify adequate clearance from all moving parts with engine off.
14. 14

    Vacuum test system
    Reconnect manifold gauge set to service ports. Connect vacuum pump to center port of manifold gauges. Open both high and low side valves. Start vacuum pump and pull vacuum on system for minimum 45 minutes, target 29.9 inches Hg. After 45 minutes, close both manifold valves and shut off pump. Observe gauges for 30 minutes - if vacuum holds steady, system is leak-free. If vacuum drops, locate and repair leak before proceeding.
15. 15

    Charge system with refrigerant
    With system still under vacuum, connect refrigerant supply (R-12 or R-134a matching original system) to center port of manifold gauges. Open refrigerant valve and allow vacuum to draw in refrigerant. Start engine and set AC controls to maximum cooling and high blower. Complete charging through low side only with engine running. Add refrigerant until proper charge weight is reached (per factory service manual specification for R-12, or per conversion specifications for R-134a). Monitor gauge pressures - typical running pressures are 25-35 psi low side and 180-220 psi high side for R-12 at 75°F ambient.
16. 16

    Leak test and verify operation
    With system charged and running, use leak detector (electronic or UV light if dye was added) to check all connections made during this procedure. Check compressor fittings, condenser fittings, and firewall connections. Verify cold air output from vents - center vent temperature should be 40-50°F below ambient. Let system run for 10 minutes and recheck all connections for leaks. Verify compressor cycles properly and no unusual noises are present.

Reassembly

1. Reconnect negative battery cable and verify no warning lights illuminate
2. If vehicle was raised, lower from jack stands and perform final clearance check with suspension at normal ride height
3. Verify all tools and parts have been removed from engine bay
4. Document refrigerant type and charge amount on label under hood for future service

Verification

• Start engine and operate AC system for minimum 15 minutes to verify proper operation
• Check all hose connections for signs of refrigerant leaks using leak detector
• Verify center vent temperature is 40-50°F below ambient temperature
• Confirm no unusual noises from compressor or hose vibration
• Check that compressor clutch engages and disengages properly with AC control
• Verify gauge pressures remain within normal operating range during extended operation
• Inspect engine bay for proper hose routing with no contact to hot or moving components

More procedures for this vehicle