Replace the high-side AC hose on a 1966 Chevrolet Corvette 327ci V8, including refrigerant recovery, hose removal, installation of new hose, and system recharge.

Warnings

Tools required

Parts

• AC high-side hose assembly × 1 — Use OEM specification or AC Delco equivalent
• AC O-rings (high-side fitting set) × 1 — Use OEM specification
• Refrigerant oil (mineral oil for R-12) × 1 — Use manufacturer-specified R-12 compatible oil
• R-12 refrigerant × 1 — Approximately 2-3 lbs per system 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 (should be original R-12 system unless previously converted).
4. Locate high-side hose: runs from compressor discharge port (driver side of engine) to condenser inlet (front of vehicle, passenger side).
5. Take photos of hose routing, support clip locations, and any clearance points for reference during installation.
6. Ensure refrigerant recovery machine is properly connected and functional.

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to service ports. Follow recovery machine manufacturer's procedures to fully evacuate all R-12 refrigerant from the system. Continue recovery until machine indicates system is empty and pressures read zero on manifold gauges. Recovery typically takes 15-20 minutes. Record amount of refrigerant recovered for recharge reference.
2. 2

   Access compressor discharge fitting
   Locate the high-side hose connection at the compressor discharge port on the driver side of the engine. Clean the area around the fitting with a wire brush and shop rag to remove dirt and corrosion. The fitting is a flare-type connection secured with a tube nut.
3. 3

   Disconnect hose from compressor
   Using a 3/4" flare nut wrench on the tube nut and a backup wrench on the compressor discharge port fitting, loosen and remove the tube nut. Back the nut off completely and carefully separate the hose from the compressor. Residual refrigerant oil may drip; catch with a shop rag. Immediately cap or plug the open compressor port to prevent contamination.
4. 4

   Remove hose support clips
   Trace the high-side hose from compressor to condenser, removing 2 support clips that secure the hose to the frame and body. Note the exact location of each clip for reinstallation. These clips prevent hose vibration and contact with hot or moving components.
5. 5

   Disconnect hose from condenser
   Access the condenser inlet connection at the front of the vehicle on the passenger side. Using a 5/8" flare nut wrench on the tube nut and a backup wrench on the condenser fitting, loosen and remove the tube nut. Separate the hose from the condenser inlet. Cap or plug the open condenser port immediately.
6. 6

   Remove old high-side hose
   Carefully remove the entire high-side hose assembly from the vehicle, noting its routing path. Inspect the old hose for signs of damage, rubbing, or deterioration. Verify the new hose matches the configuration and length of the original.
7. 7

   Prepare new hose and fittings
   Inspect the new high-side hose for any shipping damage. Install new O-rings on both hose end fittings, lightly coating them with clean refrigerant oil (mineral oil for R-12 systems). Do not reuse old O-rings. Remove caps from compressor and condenser ports.
8. 8

   Route and position new hose
   Route the new high-side hose following the exact path of the original, ensuring it does not contact exhaust components, sharp edges, or moving parts. Position hose ends at both compressor discharge and condenser inlet fittings before tightening either connection.
9. 9

   Connect hose to condenser
   Thread the tube nut onto the condenser inlet fitting by hand to ensure proper thread engagement. Using a 5/8" flare nut wrench and backup wrench, tighten the fitting to 20-25 ft-lbs. Do not overtighten as this can damage the flare seat.
10. 10

    Connect hose to compressor
    Thread the tube nut onto the compressor discharge port fitting by hand. Using a 3/4" flare nut wrench and backup wrench, tighten the fitting to 20-25 ft-lbs. Ensure the hose is not twisted or kinked during final tightening.
11. 11

    Install hose support clips
    Reinstall the 2 support clips in their original locations, ensuring the hose is secured but not pinched. Verify the hose has adequate clearance from all moving parts, exhaust components, and sharp edges throughout its full length.
12. 12

    Evacuate AC system
    Connect vacuum pump to AC service ports via manifold gauge set. Evacuate the system to pull a deep vacuum (minimum 29 inches Hg). Continue vacuum for 30-45 minutes to remove all air and moisture from the system. Monitor vacuum gauge for any loss of vacuum indicating a leak.
13. 13

    Leak test system
    Close manifold gauge valves and shut off vacuum pump. Observe vacuum gauge for 10 minutes. Vacuum should hold steady with no loss. If vacuum drops, there is a leak that must be located and repaired before proceeding with recharge.
14. 14

    Recharge AC system
    With system under vacuum, connect R-12 refrigerant source to manifold gauge set. Charge the system with the amount of R-12 recovered plus any additional needed to meet system capacity (typically 2.5-3.0 lbs total for 1966 Corvette). Charge liquid R-12 into the high side with the engine off until the system stops accepting charge, then complete the charge as vapor into the low side with the engine running and AC on maximum. Never charge liquid refrigerant into the low side, as this can damage the compressor.

Reassembly

1. Double-check all fittings are properly tightened and all support clips are installed.
2. Verify hose routing matches original configuration with no interference or rubbing points.
3. Ensure no tools or materials are left in engine compartment.

Verification

• Start engine and turn AC to maximum cool with blower on high.
• Verify AC compressor engages and remains engaged.
• Check high-side hose connections at compressor and condenser for any signs of refrigerant leakage (frost formation or oil residue).
• Monitor AC manifold gauges: high-side pressure should stabilize between 200-250 PSI with ambient temperature around 80°F.
• Verify cold air output from dashboard vents within 2-3 minutes of operation.
• Allow system to run for 10 minutes and recheck all connections for leaks.
• Confirm hose does not contact any moving parts or hot surfaces during engine operation.

More procedures for this vehicle